Compiller works VERY slow for big amout of inlined code

It probably is a bug. Looking at what happens it is probably something to do with allocation of local slots. It should however not keep trying this long. In this example inlining is a bad thing to do as quite some nontrivial stuff happens in joinItems and even in join. You are absolutely blowing up the code size without real reason to do so.The JVM is quite efficient in doing these things for you if it is the right thing to do.