diff --git a/AppKit/CPStringDrawing.j b/AppKit/CPStringDrawing.j
index 859c23926..fbd174592 100644
--- a/AppKit/CPStringDrawing.j
+++ b/AppKit/CPStringDrawing.j
@@ -24,6 +24,7 @@
 
 @import "CPPlatformString.j"
 
+var CPStringSizeWithFontInWidthCache = {};
 
 @implementation CPString (CPStringDrawing)
 
@@ -50,7 +51,17 @@
 
 - (CGSize)sizeWithFont:(CPFont)aFont inWidth:(float)aWidth
 {
-    return [CPPlatformString sizeOfString:self withFont:aFont forWidth:aWidth];
+    var cacheKey = self + [aFont cssString] + aWidth;
+        size = CPStringSizeWithFontInWidthCache[cacheKey];
+
+    if (size === undefined)
+    {
+        size = [CPPlatformString sizeOfString:self withFont:aFont forWidth:aWidth];
+        CPStringSizeWithFontInWidthCache[cacheKey] = size;
+    }
+
+    return size;
 }
 
+
 @end