diff --git a/java/java-tests/testSrc/com/intellij/editor/LineSetIncrementalUpdateTest.java b/java/java-tests/testSrc/com/intellij/editor/LineSetIncrementalUpdateTest.java
index 1fb719f8f765..7fd258438a7b 100644
--- a/java/java-tests/testSrc/com/intellij/editor/LineSetIncrementalUpdateTest.java
+++ b/java/java-tests/testSrc/com/intellij/editor/LineSetIncrementalUpdateTest.java
@@ -24,8 +24,11 @@ package com.intellij.editor;
 
 import com.intellij.openapi.command.WriteCommandAction;
 import com.intellij.openapi.editor.Document;
+import com.intellij.openapi.editor.EditorFactory;
 import com.intellij.openapi.editor.impl.LineSet;
+import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.testFramework.LightCodeInsightTestCase;
+import com.intellij.testFramework.PlatformTestUtil;
 import org.jetbrains.annotations.NonNls;
 
 public class LineSetIncrementalUpdateTest extends LightCodeInsightTestCase {
@@ -124,4 +127,18 @@ public class LineSetIncrementalUpdateTest extends LightCodeInsightTestCase {
       }
     }.execute().throwException();
   }
+
+  public void testTypingInLongLinePerformance() {
+    String longLine = StringUtil.repeat("a ", 200000);
+    PlatformTestUtil.startPerformanceTest("Document changes in a long line", 1000, () -> {
+      Document document = EditorFactory.getInstance().createDocument("a\n" + longLine + "<caret>" + longLine + "\n");
+      WriteCommandAction.runWriteCommandAction(getProject(), () -> {
+        for (int i = 0; i < 1000; i++) {
+          int offset = i * 2 + longLine.length();
+          assertEquals(1, document.getLineNumber(offset));
+          document.insertString(offset, "b");
+        }
+      });
+    }).cpuBound().assertTiming();
+  }
 }
\ No newline at end of file
diff --git a/platform/core-impl/src/com/intellij/openapi/editor/impl/LineSet.java b/platform/core-impl/src/com/intellij/openapi/editor/impl/LineSet.java
index b63988dba706..b4033a107c84 100644
--- a/platform/core-impl/src/com/intellij/openapi/editor/impl/LineSet.java
+++ b/platform/core-impl/src/com/intellij/openapi/editor/impl/LineSet.java
@@ -18,6 +18,7 @@ package com.intellij.openapi.editor.impl;
 import com.intellij.openapi.editor.ex.LineIterator;
 import com.intellij.openapi.util.text.LineTokenizer;
 import com.intellij.util.BitUtil;
+import com.intellij.util.text.CharArrayUtil;
 import com.intellij.util.text.MergingCharSequence;
 import gnu.trove.TByteArrayList;
 import gnu.trove.TIntArrayList;
@@ -65,11 +66,44 @@ public class LineSet{
   }
 
   @NotNull
-  LineSet update(@NotNull CharSequence prevText, int _start, int _end, @NotNull CharSequence replacement, boolean wholeTextReplaced) {
+  LineSet update(@NotNull CharSequence prevText, int start, int end, @NotNull CharSequence replacement, boolean wholeTextReplaced) {
     if (myLength == 0) {
       return createLineSet(replacement, !wholeTextReplaced);
     }
 
+    LineSet result = isSingleLineChange(prevText, start, end, replacement)
+                     ? updateInsideOneLine(findLineIndex(start), replacement.length() - (end - start))
+                     : genericUpdate(prevText, start, end, replacement);
+
+    if (doTest) {
+      MergingCharSequence newText = new MergingCharSequence(
+        new MergingCharSequence(prevText.subSequence(0, start), replacement),
+        prevText.subSequence(end, prevText.length()));
+      result.checkEquals(createLineSet(newText));
+    }
+    return wholeTextReplaced ? result.clearModificationFlags() : result;
+  }
+
+  private boolean isSingleLineChange(@NotNull CharSequence prevText, int start, int end, @NotNull CharSequence replacement) {
+    if (start == 0 && end == myLength && replacement.length() == 0) return false;
+
+    int startLine = findLineIndex(start);
+    return startLine == findLineIndex(end) && !CharArrayUtil.containLineBreaks(replacement) && !isLastEmptyLine(startLine);
+  }
+
+  @NotNull
+  private LineSet updateInsideOneLine(int line, int lengthDelta) {
+    int[] starts = myStarts.clone();
+    for (int i = line + 1; i < starts.length; i++) {
+      starts[i] += lengthDelta;
+    }
+
+    byte[] flags = myFlags.clone();
+    flags[line] |= MODIFIED_MASK;
+    return new LineSet(starts, flags, myLength + lengthDelta);
+  }
+
+  private LineSet genericUpdate(CharSequence prevText, int _start, int _end, CharSequence replacement) {
     int startOffset = _start;
     if (replacement.length() > 0 && replacement.charAt(0) == '\n' && startOffset > 0 && prevText.charAt(startOffset - 1) == '\r') {
       startOffset--;
@@ -90,14 +124,7 @@ public class LineSet{
       prevText.subSequence(_end, endOffset));
 
     LineSet patch = createLineSet(replacement, true);
-    LineSet applied = applyPatch(startOffset, endOffset, startLine, endLine, patch);
-    if (doTest) {
-      final MergingCharSequence newText = new MergingCharSequence(
-        new MergingCharSequence(prevText.subSequence(0, startOffset), replacement),
-        prevText.subSequence(endOffset, prevText.length()));
-      applied.checkEquals(createLineSet(newText));
-    }
-    return wholeTextReplaced ? applied.clearModificationFlags() : applied;
+    return applyPatch(startOffset, endOffset, startLine, endLine, patch);
   }
 
   private void checkEquals(@NotNull LineSet fresh) {