The bug 250793 is no longer reproducable in 2020 R2 version.
Regarding bug 252537, it's still being investigated and will let you know once it gets fixed.
Though I haven't seen these mesh control related issues (crashing and slowing the process) reported by other users, I will take one of the complex models posted in application examples and try to see if the issues can be reproduced. I think these could be mostly model specific issues. I am also checking with the development team if these issues were already reported (again I don't think so because the bugs that were submitted were not marked as duplicate, indicating that these might not have been encountered with other models). I will keep you posted.