diff -r 000000000000 -r 6474c204b198 js/src/devtools/gc/tests/dslots.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/devtools/gc/tests/dslots.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,26 @@
+//Benchmark to measure overhead of dslots allocation and deallocation
+
+function Object0() {};
+function Object1() { this.a=1; };
+function Object2() { this.a=1; this.b=1; };
+function Object3() { this.a=1; this.b=1; this.c=1; };
+function Object4() { this.a=1; this.b=1; this.c=1; this.d=1; };
+function Object5() { this.a=1; this.b=1; this.c=1; this.d=1; this.e=1; };
+
+function test() {
+    var N = 1e5;
+    gc();
+
+    for(var i = 0; i<=5; i++)
+    {
+        var tmp = i==0 ? Object0 : i==1 ? Object1 : i==2 ? Object2 : i==3 ? Object3 : i==4 ? Object4 : Object5;
+        for (var j = 0; j != N; j++) {
+            var a = new tmp();
+        }
+        gc();
+    }
+}
+
+for(var i = 0; i<=5; i++) {
+    test();
+}