What commands, in particular?
I admit that perhaps there is a configurable lag built in (it would make sense to do so) and while there are other examples that I know bother me, this is the one that jumped out straight away. I'd have to dig back in to have more specifics.
M-x is basically instant for me, though. So, not sure why anything like that would be slow.
Good luck getting it fixed, if you are still trying. A basic profiler-start, type, profiler-stop, profiler-report can probably pay the blame easily.