diff -r 9d011ab3c192 -r 71e5cd5b29bc rt/vm/src/main/java/org/apidesign/vm4brwsr/ByteCodeToJavaScript.java
--- a/rt/vm/src/main/java/org/apidesign/vm4brwsr/ByteCodeToJavaScript.java	Wed Sep 02 23:20:01 2015 +0200
+++ b/rt/vm/src/main/java/org/apidesign/vm4brwsr/ByteCodeToJavaScript.java	Sun Jan 24 14:31:36 2016 +0100
@@ -775,8 +775,15 @@
                     smapper.replace(this, VarType.DOUBLE, "(@1 / @2)", smapper.getD(1), smapper.popD());
                     break;
                 case opc_irem:
-                    smapper.replace(this, VarType.INTEGER, "(@1).mod32(@2)",
+//
+// direct check yields few percents
+// in case of firefox 5.8s/4.6.s
+                    smapper.replace(this, VarType.INTEGER, "((@1) % (@2))",
                          smapper.getI(1), smapper.popI());
+// with myNum being local variable in the generated script
+// it compiles and computes 5000 primes in 6s
+//                    smapper.replace(this, VarType.INTEGER, "myNum.mod32(@1, @2)",
+//                         smapper.getI(1), smapper.popI());
                     break;
                 case opc_lrem:
                     smapper.replace(this, VarType.LONG, "(@1).mod64(@2)",