diff --git a/addons/search/replace_matches.cpp b/addons/search/replace_matches.cpp
--- a/addons/search/replace_matches.cpp
+++ b/addons/search/replace_matches.cpp
@@ -254,6 +254,14 @@
         emit replaceStatus(doc->url());
     }
 
+    // Highlighting slows down replacement especially on long lines
+    // Disable highlighting
+    QString mode = doc->mode();
+    QString highLight = doc->highlightingMode();
+    doc->setMode(QStringLiteral("Normal"));
+    doc->setHighlightingMode(QStringLiteral("None"));
+
+
     // Create a vector of moving ranges for updating the tree-view after replace
     QVector<KTextEditor::MovingRange*> matches;
     QVector<bool> replaced;
@@ -297,5 +305,8 @@
     qDeleteAll(matches);
 
     m_rootIndex++;
+    doc->setMode(mode);
+    doc->setHighlightingMode(highLight);
+
     emit replaceNextMatch();
 }