the second time a file is requested, maybe recompile everything or see if something else has recompiled it.

I know, right!?

but, you see the karma file watcher might see that the file has changed before the grunt compiler sees it and compiles it. so, only if you have an external compiler configured do you suffer this delay and only on a recompile (which a jenkins build, or single-run will never see).

So in the end it's only slower when you are running without a grunt pipeline (or whatever compiles js) and it has to run ruby to compile the slim anyway. and that's super slow as it is...