Hey, I've just run into the issue slowing down another of my saves significantly in 5.0.1 (10-20 second halt between turns), so I'll be waiting for the patch and I'll see if I can confirm it fixes that one.
EDIT: Also, I'm not really sure why the discovered_world directory is missing, given that it's present in my zipped and unzipped versions. Maybe it got messed up somewhere in the decompression process.