Performance optimisation:

*) caching last font and trying to reuse it during editor size recalculation (used to perform a call to the lock-protected font registry for every document symbol)
*) register highlighters in bulk mode if necessary during indents pass processing;

platform/core-impl/src/com/intellij/util/DocumentUtil.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2000-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.util;
+
+import com.intellij.openapi.editor.Document;
+import com.intellij.openapi.editor.ex.DocumentEx;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Is intended to hold utility methods to use during {@link Document} processing.
+ * 
+ * @author Denis Zhdanov
+ * @since 5/16/12 10:12 AM
+ */
+public class DocumentUtil {
+
+  private DocumentUtil() {
+  }
+  
+  // TODO den add doc
+  public static void executeInBulk(@NotNull Document document, final boolean executeInBulk, @NotNull Runnable task) {
+    if (!(document instanceof DocumentEx)) {
+      task.run();
+      return;
+    }
+
+    DocumentEx documentEx = (DocumentEx)document;
+    if (executeInBulk == documentEx.isInBulkUpdate()) {
+      task.run();
+      return;
+    }
+
+    documentEx.setInBulkUpdate(executeInBulk);
+    try {
+      task.run();
+    }
+    finally {
+      documentEx.setInBulkUpdate(!executeInBulk);
+    }
+  }
+}

platform/lang-impl/src/com/intellij/codeInsight/daemon/impl/IndentsPass.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2010 JetBrains s.r.o.
+ * Copyright 2000-2012 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,6 +41,7 @@ import com.intellij.openapi.util.Key;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.tree.TokenSet;
+import com.intellij.util.DocumentUtil;
 import com.intellij.util.containers.IntStack;
 import com.intellij.util.text.CharArrayUtil;
 import org.jetbrains.annotations.NotNull;
@@ -231,8 +232,8 @@ public class IndentsPass extends TextEditorHighlightingPass implements DumbAware
     if (stamp != null && stamp.longValue() == nowStamp()) return;
 
     List<RangeHighlighter> oldHighlighters = myEditor.getUserData(INDENT_HIGHLIGHTERS_IN_EDITOR_KEY);
-    List<RangeHighlighter> newHighlighters = new ArrayList<RangeHighlighter>();
-    MarkupModel mm = myEditor.getMarkupModel();
+    final List<RangeHighlighter> newHighlighters = new ArrayList<RangeHighlighter>();
+    final MarkupModel mm = myEditor.getMarkupModel();
 
     int curRange = 0;
 
@@ -264,9 +265,16 @@ public class IndentsPass extends TextEditorHighlightingPass implements DumbAware
       }
     }
 
-    for (; curRange < myRanges.size(); curRange++) {
-      newHighlighters.add(createHighlighter(mm, myRanges.get(curRange)));
-    }
+    final int startRangeIndex = curRange;
+    DocumentUtil.executeInBulk(myDocument, myRanges.size() > 10000, new Runnable() {
+      @Override
+      public void run() {
+        for (int i = startRangeIndex; i < myRanges.size(); i++) {
+          newHighlighters.add(createHighlighter(mm, myRanges.get(i)));
+        }
+      }
+    });
+    
 
     myEditor.putUserData(INDENT_HIGHLIGHTERS_IN_EDITOR_KEY, newHighlighters);
     myEditor.putUserData(LAST_TIME_INDENTS_BUILT, nowStamp());

platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java

@@ -6060,6 +6060,7 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
         List<? extends SoftWrap> softWraps = getSoftWrapModel().getRegisteredSoftWraps();
         int softWrapsIndex = -1;
 
+        FontInfo lastFontInfo = null;
         for (int line = 0; line < lineCount; line++) {
           if (myLineWidths.getQuick(line) != -1) continue;
           if (line == lineCount - 1) {
@@ -6158,7 +6159,10 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
                 }
               }
               else {
-                x += ComplementaryFontsRegistry.getFontAbleToDisplay(c, fontSize, fontType, fontName).charWidth(c);
+                if (lastFontInfo == null || !lastFontInfo.canDisplay(c)) {
+                  lastFontInfo = ComplementaryFontsRegistry.getFontAbleToDisplay(c, fontSize, fontType, fontName);
+                }
+                x += lastFontInfo.charWidth(c);
                 offset++;
               }
             }