diff --git a/docs/pages/release_notes.md b/docs/pages/release_notes.md
index 34f16eb60f..191d9f5e87 100644
--- a/docs/pages/release_notes.md
+++ b/docs/pages/release_notes.md
@@ -185,6 +185,7 @@ are deprecated as internal API.
 *   [#2727](https://github.com/pmd/pmd/pull/2727): Cleanup: replace indexOf() < 0 with contains - [XenoAmess](https://github.com/XenoAmess)
 *   [#2728](https://github.com/pmd/pmd/pull/2728): Cleanup: javadoc issues - [XenoAmess](https://github.com/XenoAmess)
 *   [#2729](https://github.com/pmd/pmd/pull/2729): Cleanup: use print instead of printf if no format exists - [XenoAmess](https://github.com/XenoAmess)
+*   [#2730](https://github.com/pmd/pmd/pull/2730): Cleanup: StringBuilder issues - [XenoAmess](https://github.com/XenoAmess)
 *   [#2731](https://github.com/pmd/pmd/pull/2731): Cleanup: avoid compiling Patterns repeatedly - [XenoAmess](https://github.com/XenoAmess)
 *   [#2732](https://github.com/pmd/pmd/pull/2732): Cleanup: use StandardCharsets instead of Charset.forName - [XenoAmess](https://github.com/XenoAmess) 
 *   [#2734](https://github.com/pmd/pmd/pull/2734): Cleanup: use try with resources - [XenoAmess](https://github.com/XenoAmess)
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cli/PMDCommandLineInterface.java b/pmd-core/src/main/java/net/sourceforge/pmd/cli/PMDCommandLineInterface.java
index 58af4c1bd2..8642562b11 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cli/PMDCommandLineInterface.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cli/PMDCommandLineInterface.java
@@ -60,10 +60,10 @@ public final class PMDCommandLineInterface {
     public static String buildUsageText(JCommander jcommander) {
         StringBuilder usage = new StringBuilder();
 
-        String allCommandsDescription = null;
+        StringBuilder allCommandsDescription = null;
         if (jcommander != null && jcommander.getCommands() != null) {
             for (String command : jcommander.getCommands().keySet()) {
-                allCommandsDescription += jcommander.getCommandDescription(command) + PMD.EOL;
+                allCommandsDescription.append(jcommander.getCommandDescription(command)).append(PMD.EOL);
             }
         }
 
@@ -143,7 +143,7 @@ public final class PMDCommandLineInterface {
             Renderer renderer = RendererFactory.createRenderer(reportName, new Properties());
             buf.append("   ").append(reportName).append(": ");
             if (!reportName.equals(renderer.getName())) {
-                buf.append(" Deprecated alias for '" + renderer.getName()).append(PMD.EOL);
+                buf.append(" Deprecated alias for '").append(renderer.getName()).append(PMD.EOL);
                 continue;
             }
             buf.append(renderer.getDescription()).append(PMD.EOL);
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cpd/VSRenderer.java b/pmd-core/src/main/java/net/sourceforge/pmd/cpd/VSRenderer.java
index f34622e2f0..cc3af3f2d2 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cpd/VSRenderer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cpd/VSRenderer.java
@@ -33,9 +33,8 @@ public class VSRenderer implements Renderer, CPDRenderer {
             for (Iterator<Mark> iterator = match.iterator(); iterator.hasNext();) {
                 mark = iterator.next();
                 writer.append(mark.getFilename())
-                    .append('(').append(String.valueOf(mark.getBeginLine())).append("):")
-                    .append(" Between lines " + mark.getBeginLine() + " and "
-                        + (mark.getBeginLine() + match.getLineCount()) + PMD.EOL);
+                        .append('(').append(String.valueOf(mark.getBeginLine())).append("):")
+                        .append(" Between lines ").append(String.valueOf(mark.getBeginLine())).append(" and ").append(String.valueOf(mark.getBeginLine() + match.getLineCount())).append(PMD.EOL);
             }
         }
         writer.flush();
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/dfa/report/ReportHTMLPrintVisitor.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/dfa/report/ReportHTMLPrintVisitor.java
index 682dbbc587..af06618833 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/dfa/report/ReportHTMLPrintVisitor.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/dfa/report/ReportHTMLPrintVisitor.java
@@ -131,8 +131,7 @@ public class ReportHTMLPrintVisitor extends ReportVisitor {
 
         vnode.getParent().addNumberOfViolation(1);
         RuleViolation vio = vnode.getRuleViolation();
-        classBuf.append("<tr>" + " <td>" + vio.getMethodName() + "</td>" + " <td>" + this.displayRuleViolation(vio)
-                + "</td>" + "</tr>");
+        classBuf.append("<tr>" + " <td>").append(vio.getMethodName()).append("</td>").append(" <td>").append(this.displayRuleViolation(vio)).append("</td>").append("</tr>");
     }
 
     private void renderPackage(PackageNode pnode) {
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/CodeClimateRenderer.java b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/CodeClimateRenderer.java
index 67a27d783a..c738fac851 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/CodeClimateRenderer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/CodeClimateRenderer.java
@@ -145,27 +145,38 @@ public class CodeClimateRenderer extends AbstractIncrementingRenderer {
     }
 
     private <T> String getBody() {
-        String result = "## " + rule.getName() + "\\n\\n" + "Since: PMD " + rule.getSince() + "\\n\\n" + "Priority: "
-            + rule.getPriority() + "\\n\\n"
-            + "[Categories](https://github.com/codeclimate/platform/blob/master/spec/analyzers/SPEC.md#categories): "
-            + Arrays.toString(getCategories()).replaceAll("[\\[\\]]", "") + "\\n\\n"
-            + "[Remediation Points](https://github.com/codeclimate/platform/blob/master/spec/analyzers/SPEC.md#remediation-points): "
-            + getRemediationPoints() + "\\n\\n" + cleaned(rule.getDescription());
+        StringBuilder result = new StringBuilder();
+        result.append("## ")
+                .append(rule.getName())
+                .append("\\n\\n")
+                .append("Since: PMD ")
+                .append(rule.getSince())
+                .append("\\n\\n")
+                .append("Priority: ")
+                .append(rule.getPriority())
+                .append("\\n\\n")
+                .append("[Categories](https://github.com/codeclimate/platform/blob/master/spec/analyzers/SPEC.md#categories): ")
+                .append(Arrays.toString(getCategories()).replaceAll("[\\[\\]]", ""))
+                .append("\\n\\n")
+                .append("[Remediation Points](https://github.com/codeclimate/platform/blob/master/spec/analyzers/SPEC.md#remediation-points): ")
+                .append(getRemediationPoints())
+                .append("\\n\\n")
+                .append(cleaned(rule.getDescription()));
 
         if (!rule.getExamples().isEmpty()) {
-            result += "\\n\\n### Example:\\n\\n";
+            result.append("\\n\\n### Example:\\n\\n");
 
             for (String snippet : rule.getExamples()) {
                 String exampleSnippet = snippet.replaceAll("\\n", "\\\\n");
                 exampleSnippet = exampleSnippet.replaceAll("\\t", "\\\\t");
-                result += "```java\\n" + exampleSnippet + "\\n```  ";
+                result.append("```java\\n").append(exampleSnippet).append("\\n```  ");
             }
         }
 
         if (!rule.getPropertyDescriptors().isEmpty()) {
-            result += "\\n\\n### [PMD properties](" + PMD_PROPERTIES_URL + ")\\n\\n";
-            result += "Name | Value | Description\\n";
-            result += "--- | --- | ---\\n";
+            result.append("\\n\\n### [PMD properties](").append(PMD_PROPERTIES_URL).append(")\\n\\n");
+            result.append("Name | Value | Description\\n");
+            result.append("--- | --- | ---\\n");
 
             for (PropertyDescriptor<?> property : rule.getPropertyDescriptors()) {
                 String propertyName = property.name().replaceAll("\\_", "\\\\_");
@@ -182,10 +193,10 @@ public class CodeClimateRenderer extends AbstractIncrementingRenderer {
                 }
                 propertyValue = propertyValue.replaceAll("(\n|\r\n|\r)", "\\\\n");
 
-                result += propertyName + " | " + propertyValue + " | " + property.description() + "\\n";
+                result.append(propertyName).append(" | ").append(propertyValue).append(" | ").append(property.description()).append("\\n");
             }
         }
-        return cleaned(result);
+        return cleaned(result.toString());
     }
 
     private String cleaned(String original) {
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/HTMLRenderer.java b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/HTMLRenderer.java
index 4dae8b745d..5f37db9be2 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/HTMLRenderer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/HTMLRenderer.java
@@ -128,12 +128,13 @@ public class HTMLRenderer extends AbstractIncrementingRenderer {
                 buf.append(" bgcolor=\"lightgrey\"");
             }
             colorize = !colorize;
-            buf.append("> " + PMD.EOL);
-            buf.append("<td align=\"center\">" + violationCount + "</td>" + PMD.EOL);
-            buf.append("<td width=\"*%\">"
-                    + renderFileName(rv.getFilename(), rv.getBeginLine())
-                    + "</td>" + PMD.EOL);
-            buf.append("<td align=\"center\" width=\"5%\">" + Integer.toString(rv.getBeginLine()) + "</td>" + PMD.EOL);
+            buf.append("> ").append(PMD.EOL);
+            buf.append("<td align=\"center\">").append(violationCount).append("</td>").append(PMD.EOL);
+            buf.append("<td width=\"*%\">")
+                    .append(renderFileName(rv.getFilename(), rv.getBeginLine()))
+                    .append("</td>")
+                    .append(PMD.EOL);
+            buf.append("<td align=\"center\" width=\"5%\">").append(rv.getBeginLine()).append("</td>").append(PMD.EOL);
 
             String d = StringEscapeUtils.escapeHtml4(rv.getDescription());
 
@@ -141,8 +142,8 @@ public class HTMLRenderer extends AbstractIncrementingRenderer {
             if (StringUtils.isNotBlank(infoUrl)) {
                 d = "<a href=\"" + infoUrl + "\">" + d + "</a>";
             }
-            buf.append("<td width=\"*\">" + d + "</td>" + PMD.EOL);
-            buf.append("</tr>" + PMD.EOL);
+            buf.append("<td width=\"*\">").append(d).append("</td>").append(PMD.EOL);
+            buf.append("</tr>").append(PMD.EOL);
             writer.write(buf.toString());
             violationCount++;
         }
@@ -182,10 +183,10 @@ public class HTMLRenderer extends AbstractIncrementingRenderer {
                 buf.append(" bgcolor=\"lightgrey\"");
             }
             colorize = !colorize;
-            buf.append("> " + PMD.EOL);
-            buf.append("<td>" + renderFileName(pe.getFile(), -1) + "</td>" + PMD.EOL);
-            buf.append("<td><pre>" + pe.getDetail() + "</pre></td>" + PMD.EOL);
-            buf.append("</tr>" + PMD.EOL);
+            buf.append("> ").append(PMD.EOL);
+            buf.append("<td>").append(renderFileName(pe.getFile(), -1)).append("</td>").append(PMD.EOL);
+            buf.append("<td><pre>").append(pe.getDetail()).append("</pre></td>").append(PMD.EOL);
+            buf.append("</tr>").append(PMD.EOL);
             writer.write(buf.toString());
         }
         writer.write("</table>");
@@ -210,15 +211,14 @@ public class HTMLRenderer extends AbstractIncrementingRenderer {
                 buf.append(" bgcolor=\"lightgrey\"");
             }
             colorize = !colorize;
-            buf.append("> " + PMD.EOL);
+            buf.append("> ").append(PMD.EOL);
             RuleViolation rv = sv.getRuleViolation();
-            buf.append("<td align=\"left\">" + renderFileName(rv.getFilename(), rv.getBeginLine()) + "</td>" + PMD.EOL);
-            buf.append("<td align=\"center\">" + rv.getBeginLine() + "</td>" + PMD.EOL);
-            buf.append("<td align=\"center\">" + renderRuleName(rv.getRule()) + "</td>" + PMD.EOL);
-            buf.append("<td align=\"center\">" + (sv.suppressedByNOPMD() ? "NOPMD" : "Annotation") + "</td>" + PMD.EOL);
-            buf.append("<td align=\"center\">" + (sv.getUserMessage() == null ? "" : sv.getUserMessage()) + "</td>"
-                    + PMD.EOL);
-            buf.append("</tr>" + PMD.EOL);
+            buf.append("<td align=\"left\">").append(renderFileName(rv.getFilename(), rv.getBeginLine())).append("</td>").append(PMD.EOL);
+            buf.append("<td align=\"center\">").append(rv.getBeginLine()).append("</td>").append(PMD.EOL);
+            buf.append("<td align=\"center\">").append(renderRuleName(rv.getRule())).append("</td>").append(PMD.EOL);
+            buf.append("<td align=\"center\">").append(sv.suppressedByNOPMD() ? "NOPMD" : "Annotation").append("</td>").append(PMD.EOL);
+            buf.append("<td align=\"center\">").append(sv.getUserMessage() == null ? "" : sv.getUserMessage()).append("</td>").append(PMD.EOL);
+            buf.append("</tr>").append(PMD.EOL);
             writer.write(buf.toString());
         }
         writer.write("</table>");
@@ -243,10 +243,10 @@ public class HTMLRenderer extends AbstractIncrementingRenderer {
                 buf.append(" bgcolor=\"lightgrey\"");
             }
             colorize = !colorize;
-            buf.append("> " + PMD.EOL);
-            buf.append("<td>" + renderRuleName(ce.rule()) + "</td>" + PMD.EOL);
-            buf.append("<td>" + ce.issue() + "</td>" + PMD.EOL);
-            buf.append("</tr>" + PMD.EOL);
+            buf.append("> ").append(PMD.EOL);
+            buf.append("<td>").append(renderRuleName(ce.rule())).append("</td>").append(PMD.EOL);
+            buf.append("<td>").append(ce.issue()).append("</td>").append(PMD.EOL);
+            buf.append("</tr>").append(PMD.EOL);
             writer.write(buf.toString());
         }
         writer.write("</table>");
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/IDEAJRenderer.java b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/IDEAJRenderer.java
index 4147ef0404..0cc16dc8d9 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/IDEAJRenderer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/IDEAJRenderer.java
@@ -66,7 +66,7 @@ public class IDEAJRenderer extends AbstractIncrementingRenderer {
         while (violations.hasNext()) {
             buf.setLength(0);
             RuleViolation rv = violations.next();
-            buf.append(rv.getDescription() + PMD.EOL);
+            buf.append(rv.getDescription()).append(PMD.EOL);
             buf.append(" at ").append(getFullyQualifiedClassName(rv.getFilename(), sourcePath)).append(".method(");
             buf.append(getSimpleFileName(rv.getFilename())).append(':').append(rv.getBeginLine()).append(')')
                     .append(PMD.EOL);
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextColorRenderer.java b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextColorRenderer.java
index bc2c95c706..c4a960c464 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextColorRenderer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextColorRenderer.java
@@ -125,17 +125,41 @@ public class TextColorRenderer extends AbstractAccumulatingRenderer {
             String nextFile = determineFileName(rv.getFilename());
             if (!nextFile.equals(lastFile)) {
                 lastFile = nextFile;
-                buf.append(this.yellowBold + "*" + this.colorReset + " file: " + this.whiteBold
-                        + this.getRelativePath(lastFile) + this.colorReset + PMD.EOL);
+                buf.append(this.yellowBold)
+                        .append("*")
+                        .append(this.colorReset)
+                        .append(" file: ")
+                        .append(this.whiteBold)
+                        .append(this.getRelativePath(lastFile))
+                        .append(this.colorReset)
+                        .append(PMD.EOL);
             }
-            buf.append(
-                    this.green + "    src:  " + this.cyan + lastFile.substring(lastFile.lastIndexOf(File.separator) + 1)
-                            + this.colorReset + ":" + this.cyan + rv.getBeginLine()
-                            + (rv.getEndLine() == -1 ? "" : ":" + rv.getEndLine()) + this.colorReset + PMD.EOL);
-            buf.append(this.green + "    rule: " + this.colorReset + rv.getRule().getName() + PMD.EOL);
-            buf.append(this.green + "    msg:  " + this.colorReset + rv.getDescription() + PMD.EOL);
-            buf.append(this.green + "    code: " + this.colorReset + this.getLine(lastFile, rv.getBeginLine()) + PMD.EOL
-                    + PMD.EOL);
+            buf.append(this.green)
+                    .append("    src:  ")
+                    .append(this.cyan)
+                    .append(lastFile.substring(lastFile.lastIndexOf(File.separator) + 1))
+                    .append(this.colorReset).append(":")
+                    .append(this.cyan)
+                    .append(rv.getBeginLine())
+                    .append(rv.getEndLine() == -1 ? "" : ":" + rv.getEndLine())
+                    .append(this.colorReset)
+                    .append(PMD.EOL);
+            buf.append(this.green)
+                    .append("    rule: ")
+                    .append(this.colorReset)
+                    .append(rv.getRule().getName())
+                    .append(PMD.EOL);
+            buf.append(this.green)
+                    .append("    msg:  ")
+                    .append(this.colorReset)
+                    .append(rv.getDescription())
+                    .append(PMD.EOL);
+            buf.append(this.green)
+                    .append("    code: ")
+                    .append(this.colorReset)
+                    .append(this.getLine(lastFile, rv.getBeginLine()))
+                    .append(PMD.EOL)
+                    .append(PMD.EOL);
             writer.write(buf.toString());
         }
         writer.write(PMD.EOL + PMD.EOL);
@@ -155,11 +179,26 @@ public class TextColorRenderer extends AbstractAccumulatingRenderer {
             String nextFile = determineFileName(error.getFile());
             if (!nextFile.equals(lastFile)) {
                 lastFile = nextFile;
-                buf.append(this.redBold + "*" + this.colorReset + " file: " + this.whiteBold
-                        + this.getRelativePath(lastFile) + this.colorReset + PMD.EOL);
+                buf.append(this.redBold)
+                        .append("*")
+                        .append(this.colorReset)
+                        .append(" file: ")
+                        .append(this.whiteBold)
+                        .append(this.getRelativePath(lastFile))
+                        .append(this.colorReset)
+                        .append(PMD.EOL);
             }
-            buf.append(this.green + "    err:  " + this.cyan + error.getMsg() + this.colorReset + PMD.EOL)
-                .append(this.red).append(error.getDetail()).append(colorReset).append(PMD.EOL).append(PMD.EOL);
+            buf.append(this.green)
+                    .append("    err:  ")
+                    .append(this.cyan)
+                    .append(error.getMsg())
+                    .append(this.colorReset)
+                    .append(PMD.EOL)
+                    .append(this.red)
+                    .append(error.getDetail())
+                    .append(colorReset)
+                    .append(PMD.EOL)
+                    .append(PMD.EOL);
             writer.write(buf.toString());
         }
 
@@ -167,9 +206,21 @@ public class TextColorRenderer extends AbstractAccumulatingRenderer {
             buf.setLength(0);
             numberOfErrors++;
             Report.ConfigurationError error = i.next();
-            buf.append(this.redBold + "*" + this.colorReset + " rule: " + this.whiteBold
-                    + error.rule().getName() + this.colorReset + PMD.EOL);
-            buf.append(this.green + "    err:  " + this.cyan + error.issue() + this.colorReset + PMD.EOL + PMD.EOL);
+            buf.append(this.redBold)
+                    .append("*")
+                    .append(this.colorReset)
+                    .append(" rule: ")
+                    .append(this.whiteBold)
+                    .append(error.rule().getName())
+                    .append(this.colorReset)
+                    .append(PMD.EOL);
+            buf.append(this.green)
+                    .append("    err:  ")
+                    .append(this.cyan)
+                    .append(error.issue())
+                    .append(this.colorReset)
+                    .append(PMD.EOL)
+                    .append(PMD.EOL);
             writer.write(buf.toString());
         }
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextPadRenderer.java b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextPadRenderer.java
index d58226fbcd..dcf599aa18 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextPadRenderer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/TextPadRenderer.java
@@ -55,7 +55,7 @@ public class TextPadRenderer extends AbstractIncrementingRenderer {
             RuleViolation rv = violations.next();
             buf.setLength(0);
             // Filename
-            buf.append(determineFileName(rv.getFilename()) + "(");
+            buf.append(determineFileName(rv.getFilename())).append("(");
             // Line number
             buf.append(Integer.toString(rv.getBeginLine())).append(",  ");
             // Name of violated rule
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/VBHTMLRenderer.java b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/VBHTMLRenderer.java
index 9b050cbdc7..1af81231dc 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/renderers/VBHTMLRenderer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/renderers/VBHTMLRenderer.java
@@ -68,9 +68,8 @@ public class VBHTMLRenderer extends AbstractIncrementingRenderer {
             }
 
             colorize = !colorize;
-            sb.append("<td width=\"50\" align=\"right\"><font class=body>" + rv.getBeginLine()
-                    + "&nbsp;&nbsp;&nbsp;</font></td>");
-            sb.append("<td><font class=body>" + rv.getDescription() + "</font></td>");
+            sb.append("<td width=\"50\" align=\"right\"><font class=body>").append(rv.getBeginLine()).append("&nbsp;&nbsp;&nbsp;</font></td>");
+            sb.append("<td><font class=body>").append(rv.getDescription()).append("</font></td>");
             sb.append("</tr>");
             sb.append(lineSep);
             writer.write(sb.toString());
@@ -130,7 +129,7 @@ public class VBHTMLRenderer extends AbstractIncrementingRenderer {
 
     private String header() {
         StringBuilder sb = new StringBuilder(600).append("<html><head><title>PMD</title></head>")
-                .append("<style type=\"text/css\">").append("<!--" + PMD.EOL)
+                .append("<style type=\"text/css\">").append("<!--").append(PMD.EOL)
                 .append("body { background-color: white; font-family:verdana, arial, helvetica, geneva; font-size: 16px; font-style: italic; color: black; }")
                 .append(PMD.EOL)
                 .append(".title { font-family: verdana, arial, helvetica,geneva; font-size: 12px; font-weight:bold; color: white; }")
diff --git a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/symboltable/ClassScope.java b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/symboltable/ClassScope.java
index 07f6f92533..c93c0d0386 100644
--- a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/symboltable/ClassScope.java
+++ b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/symboltable/ClassScope.java
@@ -188,25 +188,25 @@ public class ClassScope extends AbstractScope {
 
     @Override
     public String toString() {
-        String res = "ClassScope (" + className + "): ";
+        StringBuilder res = new StringBuilder("ClassScope (").append(className).append("): ");
         Map<ClassNameDeclaration, List<NameOccurrence>> classNames = getClassDeclarations();
         Map<MethodNameDeclaration, List<NameOccurrence>> methodNames = getMethodDeclarations();
         Map<VariableNameDeclaration, List<NameOccurrence>> variableNames = getVariableDeclarations();
         if (!classNames.isEmpty()) {
-            res += "(" + classNames.keySet() + ")";
+            res.append('(').append(classNames.keySet()).append(')');
         }
         if (!methodNames.isEmpty()) {
             for (MethodNameDeclaration mnd : methodNames.keySet()) {
-                res += mnd.toString();
+                res.append(mnd.toString());
                 int usages = methodNames.get(mnd).size();
-                res += "(begins at line " + mnd.getNode().getBeginLine() + ", " + usages + " usages)";
-                res += ",";
+                res.append("(begins at line ").append(mnd.getNode().getBeginLine()).append(", ").append(usages).append(" usages)");
+                res.append(',');
             }
         }
         if (!variableNames.isEmpty()) {
-            res += "(" + variableNames.keySet() + ")";
+            res.append('(').append(variableNames.keySet()).append(')');
         }
-        return res;
+        return res.toString();
     }
 
     private String clipClassName(String s) {
diff --git a/pmd-test/src/main/java/net/sourceforge/pmd/AbstractRuleSetFactoryTest.java b/pmd-test/src/main/java/net/sourceforge/pmd/AbstractRuleSetFactoryTest.java
index 98cb968a5d..bfa7f0a765 100644
--- a/pmd-test/src/main/java/net/sourceforge/pmd/AbstractRuleSetFactoryTest.java
+++ b/pmd-test/src/main/java/net/sourceforge/pmd/AbstractRuleSetFactoryTest.java
@@ -102,7 +102,7 @@ public abstract class AbstractRuleSetFactoryTest {
         int invalidClassName = 0;
         int invalidRegexSuppress = 0;
         int invalidXPathSuppress = 0;
-        String messages = "";
+        StringBuilder messages = new StringBuilder();
         List<String> ruleSetFileNames = getRuleSetFileNames();
         for (String fileName : ruleSetFileNames) {
             RuleSet ruleSet = loadRuleSetByFileName(fileName);
@@ -123,13 +123,22 @@ public abstract class AbstractRuleSetFactoryTest {
                 // Is since missing ?
                 if (rule.getSince() == null) {
                     invalidSinceAttributes++;
-                    messages += "Rule " + fileName + "/" + rule.getName() + " is missing 'since' attribute" + PMD.EOL;
+                    messages.append("Rule ")
+                            .append(fileName)
+                            .append("/")
+                            .append(rule.getName())
+                            .append(" is missing 'since' attribute")
+                            .append(PMD.EOL);
                 }
                 // Is URL valid ?
                 if (rule.getExternalInfoUrl() == null || "".equalsIgnoreCase(rule.getExternalInfoUrl())) {
                     invalidExternalInfoURL++;
-                    messages += "Rule " + fileName + "/" + rule.getName() + " is missing 'externalInfoURL' attribute"
-                            + PMD.EOL;
+                    messages.append("Rule ")
+                            .append(fileName)
+                            .append("/")
+                            .append(rule.getName())
+                            .append(" is missing 'externalInfoURL' attribute")
+                            .append(PMD.EOL);
                 } else {
                     String expectedExternalInfoURL = "https?://pmd.(sourceforge.net|github.io)/.+/pmd_rules_"
                             + language.getTerseName() + "_"
@@ -139,9 +148,15 @@ public abstract class AbstractRuleSetFactoryTest {
                     if (rule.getExternalInfoUrl() == null
                             || !rule.getExternalInfoUrl().matches(expectedExternalInfoURL)) {
                         invalidExternalInfoURL++;
-                        messages += "Rule " + fileName + "/" + rule.getName()
-                                + " seems to have an invalid 'externalInfoURL' value (" + rule.getExternalInfoUrl()
-                                + "), it should be:" + expectedExternalInfoURL + PMD.EOL;
+                        messages.append("Rule ")
+                                .append(fileName)
+                                .append("/")
+                                .append(rule.getName())
+                                .append(" seems to have an invalid 'externalInfoURL' value (")
+                                .append(rule.getExternalInfoUrl())
+                                .append("), it should be:")
+                                .append(expectedExternalInfoURL)
+                                .append(PMD.EOL);
                     }
                 }
                 // Proper class name/packaging?
@@ -150,22 +165,32 @@ public abstract class AbstractRuleSetFactoryTest {
                 if (!rule.getRuleClass().equals(expectedClassName)
                         && !validXPathClassNames.contains(rule.getRuleClass())) {
                     invalidClassName++;
-                    messages += "Rule " + fileName + "/" + rule.getName() + " seems to have an invalid 'class' value ("
-                            + rule.getRuleClass() + "), it should be:" + expectedClassName + PMD.EOL;
+                    messages.append("Rule ")
+                            .append(fileName)
+                            .append("/")
+                            .append(rule.getName())
+                            .append(" seems to have an invalid 'class' value (")
+                            .append(rule.getRuleClass())
+                            .append("), it should be:")
+                            .append(expectedClassName)
+                            .append(PMD.EOL);
                 }
                 // Should not have violation suppress regex property
                 if (rule.getProperty(Rule.VIOLATION_SUPPRESS_REGEX_DESCRIPTOR) != null) {
                     invalidRegexSuppress++;
-                    messages += "Rule " + fileName + "/" + rule.getName() + " should not have '"
-                            + Rule.VIOLATION_SUPPRESS_REGEX_DESCRIPTOR.name()
-                            + "', this is intended for end user customization only." + PMD.EOL;
+                    messages.append("Rule ")
+                            .append(fileName)
+                            .append("/")
+                            .append(rule.getName())
+                            .append(" should not have '")
+                            .append(Rule.VIOLATION_SUPPRESS_REGEX_DESCRIPTOR.name())
+                            .append("', this is intended for end user customization only.")
+                            .append(PMD.EOL);
                 }
                 // Should not have violation suppress xpath property
                 if (rule.getProperty(Rule.VIOLATION_SUPPRESS_XPATH_DESCRIPTOR) != null) {
                     invalidXPathSuppress++;
-                    messages += "Rule " + fileName + "/" + rule.getName() + " should not have '"
-                            + Rule.VIOLATION_SUPPRESS_XPATH_DESCRIPTOR.name()
-                            + "', this is intended for end user customization only." + PMD.EOL;
+                    messages.append("Rule ").append(fileName).append("/").append(rule.getName()).append(" should not have '").append(Rule.VIOLATION_SUPPRESS_XPATH_DESCRIPTOR.name()).append("', this is intended for end user customization only.").append(PMD.EOL);
                 }
             }
         }