2 files changed, 9 insertions, 2 deletions
diff --git a/AUTHORS b/AUTHORS
index ef611d55..296d4150 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -51,4 +51,5 @@ a license to everyone to use it as detailed in LICENSE.)
 * Michael Bishop <mbtyke@gmail.com>
 * Roger Braun <roger@rogerbraun.net>
 * Vladimir Vukicevic <vladimir@pobox.com> (copyright owned by Mozilla Foundation)
+* Lorant Pinter <lorant.pinter@prezi.com>
 
diff --git a/src/preamble.js b/src/preamble.js
index a7731e7f..6f4b49de 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -447,7 +447,7 @@ function allocate(slab, types, allocator, ptr) {
   }
 #endif
 
-  var i = 0, type;
+  var i = 0, type, typeSize, previousType;
   while (i < size) {
     var curr = slab[i];
 
@@ -469,7 +469,13 @@ function allocate(slab, types, allocator, ptr) {
 #endif
 
     setValue(ret+i, curr, type);
-    i += Runtime.getNativeTypeSize(type);
+
+    // no need to look up size unless type changes, so cache it
+    if (previousType !== type) {
+      typeSize = Runtime.getNativeTypeSize(type);
+      previousType = type;
+    }
+    i += typeSize;
   }
 
   return ret;