diff --git a/src/buffer/katetextblock.cpp b/src/buffer/katetextblock.cpp
--- a/src/buffer/katetextblock.cpp
+++ b/src/buffer/katetextblock.cpp
@@ -21,6 +21,8 @@
 #include "katetextblock.h"
 #include "katetextbuffer.h"
 
+#include <QVarLengthArray>
+
 namespace Kate
 {
 
@@ -149,7 +151,8 @@
     }
 
     // move all cursors on the line which has the text inserted
-    QSet<TextRange *> changedRanges;
+    // remember all ranges modified, optimize for the standard case of a few ranges
+    QVarLengthArray<TextRange *, 32> changedRanges;
     for (TextCursor *cursor : qAsConst(m_cursors)) {
         // skip cursors on lines in front of the wrapped one!
         if (cursor->lineInBlock() < line) {
@@ -180,9 +183,11 @@
             cursor->m_column -= position.column();
         }
 
-        // remember range, if any
-        if (cursor->kateRange()) {
-            changedRanges.insert(cursor->kateRange());
+        // remember range, if any, avoid double insert
+        auto range = cursor->kateRange();
+        if (range && !range->isValidityCheckRequired()) {
+            range->setValidityCheckRequired();
+            changedRanges.push_back(range);
         }
     }
 
@@ -245,16 +250,19 @@
         }
 
         // move all cursors because of the unwrapped line
-        QSet<TextRange *> changedRanges;
+        // remember all ranges modified, optimize for the standard case of a few ranges
+        QVarLengthArray<TextRange *, 32> changedRanges;
         for (TextCursor *cursor : qAsConst(m_cursors)) {
             // this is the unwrapped line
             if (cursor->lineInBlock() == 0) {
                 // patch column
                 cursor->m_column += oldSizeOfPreviousLine;
 
-                // remember range, if any
-                if (cursor->kateRange()) {
-                    changedRanges.insert(cursor->kateRange());
+                // remember range, if any, avoid double insert
+                auto range = cursor->kateRange();
+                if (range && !range->isValidityCheckRequired()) {
+                    range->setValidityCheckRequired();
+                    changedRanges.push_back(range);
                 }
             }
         }
@@ -267,9 +275,11 @@
                 cursor->m_block = this;
                 m_cursors.insert(cursor);
 
-                // remember range, if any
-                if (cursor->kateRange()) {
-                    changedRanges.insert(cursor->kateRange());
+                // remember range, if any, avoid double insert
+                auto range = cursor->kateRange();
+                if (range && !range->isValidityCheckRequired()) {
+                    range->setValidityCheckRequired();
+                    changedRanges.push_back(range);
                 }
             } else {
                 newPreviousCursors.insert(cursor);
@@ -331,7 +341,8 @@
     }
 
     // move all cursors because of the unwrapped line
-    QSet<TextRange *> changedRanges;
+    // remember all ranges modified, optimize for the standard case of a few ranges
+    QVarLengthArray<TextRange *, 32> changedRanges;
     for (TextCursor *cursor : qAsConst(m_cursors)) {
         // skip cursors in lines in front of removed one
         if (cursor->lineInBlock() < line) {
@@ -347,9 +358,11 @@
         // patch line of cursor
         cursor->m_line--;
 
-        // remember range, if any
-        if (cursor->kateRange())  {
-            changedRanges.insert(cursor->kateRange());
+        // remember range, if any, avoid double insert
+        auto range = cursor->kateRange();
+        if (range && !range->isValidityCheckRequired()) {
+            range->setValidityCheckRequired();
+            changedRanges.push_back(range);
         }
     }
 
@@ -392,7 +405,8 @@
     }
 
     // move all cursors on the line which has the text inserted
-    QSet<TextRange *> changedRanges;
+    // remember all ranges modified, optimize for the standard case of a few ranges
+    QVarLengthArray<TextRange *, 32> changedRanges;
     for (TextCursor *cursor : qAsConst(m_cursors)) {
         // skip cursors not on this line!
         if (cursor->lineInBlock() != line) {
@@ -416,9 +430,12 @@
             cursor->m_column = textOfLine.size();
         }
 
+        // remember range, if any, avoid double insert
         // we only need to trigger checkValidity later if the range has feedback or might be invalidated
-        if (cursor->kateRange() && (cursor->kateRange()->feedback() || cursor->kateRange()->start().line() == cursor->kateRange()->end().line())) {
-            changedRanges.insert(cursor->kateRange());
+        auto range = cursor->kateRange();
+        if (range && !range->isValidityCheckRequired() && (range->feedback() || range->start().line() == range->end().line())) {
+            range->setValidityCheckRequired();
+            changedRanges.push_back(range);
         }
     }
 
@@ -466,7 +483,8 @@
     }
 
     // move all cursors on the line which has the text removed
-    QSet<TextRange *> changedRanges;
+    // remember all ranges modified, optimize for the standard case of a few ranges
+    QVarLengthArray<TextRange *, 32> changedRanges;
     for (TextCursor *cursor : qAsConst(m_cursors)) {
         // skip cursors not on this line!
         if (cursor->lineInBlock() != line) {
@@ -485,9 +503,12 @@
             cursor->m_column -= (range.end().column() - range.start().column());
         }
 
+        // remember range, if any, avoid double insert
         // we only need to trigger checkValidity later if the range has feedback or might be invalidated
-        if (cursor->kateRange() && (cursor->kateRange()->feedback() || cursor->kateRange()->start().line() == cursor->kateRange()->end().line())) {
-            changedRanges.insert(cursor->kateRange());
+        auto range = cursor->kateRange();
+        if (range && !range->isValidityCheckRequired() && (range->feedback() || range->start().line() == range->end().line())) {
+            range->setValidityCheckRequired();
+            changedRanges.push_back(range);
         }
     }
 
diff --git a/src/buffer/katetextrange.h b/src/buffer/katetextrange.h
--- a/src/buffer/katetextrange.h
+++ b/src/buffer/katetextrange.h
@@ -284,12 +284,12 @@
     /**
      * no copy constructor, don't allow this to be copied.
      */
-    TextRange(const TextRange &);
+    TextRange(const TextRange &) = delete;
 
     /**
      * no assignment operator, no copying around.
      */
-    TextRange &operator= (const TextRange &);
+    TextRange &operator= (const TextRange &) = delete;
 
     /**
      * Check if range is valid, used by constructor and setRange.
@@ -313,6 +313,23 @@
      */
     void fixLookup(int oldStartLine, int oldEndLine, int startLine, int endLine);
 
+    /**
+     * Mark this range for later validity checking.
+     */
+    void setValidityCheckRequired()
+    {
+        m_isCheckValidityRequired = true;
+    }
+
+    /**
+     * Does this range need validity checking?
+     * @return is checking required?
+     */
+    bool isValidityCheckRequired() const
+    {
+        return m_isCheckValidityRequired;
+    }
+
 private:
     /**
      * parent text buffer
@@ -359,6 +376,13 @@
      * Will this range invalidate itself if it becomes empty?
      */
     bool m_invalidateIfEmpty;
+
+    /**
+     * Should this range be validated?
+     * Used by KateTextBlock to avoid multiple updates without costly hashing.
+     * Reset by checkValidity().
+     */
+    bool m_isCheckValidityRequired = false;
 };
 
 }
diff --git a/src/buffer/katetextrange.cpp b/src/buffer/katetextrange.cpp
--- a/src/buffer/katetextrange.cpp
+++ b/src/buffer/katetextrange.cpp
@@ -181,6 +181,11 @@
 
 void TextRange::checkValidity(int oldStartLine, int oldEndLine, bool notifyAboutChange)
 {
+    /**
+     * in any case: reset the flag, to avoid multiple runs
+     */
+    m_isCheckValidityRequired = false;
+
     /**
      * check if any cursor is invalid or the range is zero size and it should be invalidated then
      */