diff --git a/docs/pages/release_notes.md b/docs/pages/release_notes.md
index 6215d7600e..1400af48bd 100644
--- a/docs/pages/release_notes.md
+++ b/docs/pages/release_notes.md
@@ -139,6 +139,7 @@ CPD also parses raw string literals now correctly (see [#1784](https://github.co
 *   [#1820](https://github.com/pmd/pmd/pull/1820): \[cpp] \[cpd] Improve support for raw string literals - [Maikel Steneker](https://github.com/maikelsteneker)
 *   [#1821](https://github.com/pmd/pmd/pull/1821): \[matlab] \[cpd] Matlab question mark token - [Maikel Steneker](https://github.com/maikelsteneker)
 *   [#1822](https://github.com/pmd/pmd/pull/1822): \[matlab] \[cpd] Double quoted string - [Maikel Steneker](https://github.com/maikelsteneker)
+*   [#1837](https://github.com/pmd/pmd/pull/1837): \[core] Minor performance improvements - [Michael Hausegger](https://github.com/TheRealHaui)
 *   [#1840](https://github.com/pmd/pmd/pull/1840): \[java] Whitelist serialPersistentFields - [Marcel Härle](https://github.com/marcelhaerle)
 
 {% endtocmaker %}
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cpd/GUI.java b/pmd-core/src/main/java/net/sourceforge/pmd/cpd/GUI.java
index 916276502a..fd7e436af2 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cpd/GUI.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cpd/GUI.java
@@ -421,7 +421,7 @@ public class GUI implements CPDListener {
         ignoreAnnotationsCheckbox.setEnabled(current.canIgnoreAnnotations());
         ignoreUsingsCheckbox.setEnabled(current.canIgnoreUsings());
         extensionField.setText(current.extensions()[0]);
-        boolean enableExtension = current.extensions()[0].length() == 0;
+        boolean enableExtension = current.extensions()[0].isEmpty();
         extensionField.setEnabled(enableExtension);
         extensionLabel.setEnabled(enableExtension);
     }
@@ -611,7 +611,7 @@ public class GUI implements CPDListener {
     private boolean isLegalPath(String path, LanguageConfig config) {
         String[] extensions = config.extensions();
         for (int i = 0; i < extensions.length; i++) {
-            if (path.endsWith(extensions[i]) && extensions[i].length() > 0) {
+            if (path.endsWith(extensions[i]) && !extensions[i].isEmpty()) {
                 return true;
             }
         }
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/util/designer/Designer.java b/pmd-core/src/main/java/net/sourceforge/pmd/util/designer/Designer.java
index a43fa65778..90af1421f5 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/util/designer/Designer.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/util/designer/Designer.java
@@ -939,7 +939,7 @@ public class Designer implements ClipboardOwner {
     }
 
     private String getXmlTreeCode() {
-        if (codeEditorPane.getText() != null && codeEditorPane.getText().trim().length() > 0) {
+        if (codeEditorPane.getText() != null && !codeEditorPane.getText().trim().isEmpty()) {
             Node cu = getCompilationUnit();
             return getXmlTreeCode(cu);
         }