[CI failed again](https://github.com/tcltk/tcl/actions/runs/18056877013/job/51387842541) in aaa_exit.test (build with symbols and mem-debug).

However this time it was definitely performance thing - the time ran out after 1 second (test took longer than a timeout event).

So I increased the timeout for mem-debug build (for all branches) and rewrote the tests a bit, but...

This could just be a temporary slowdown of GHA, as well as a sign of slowing down caused by the new reentrant mutex. Just kidding... although, when I think about it twice...