stripped_info is expensive

[nickdrozd]

I profiled Quick Sim running over a list of programs for 10,000 loops.

A lot of time is getting spent in strip_config and its subsidiary stripped_info.

I don't know what the solution is exactly, but I bet there is a simple change that could be applied here to speed things up.

I see from the code comments that this is a known issue. Hopefully the graph is helpful anyway.