I'm on Linux (slackware current 64-bit, with multilib), mono 6.8.0.105, Nvidia Geforce 1050ti (450.66). 16GB RAM, Ryzen 5 1600, 5.4.58 kernel
Whenever I open the world map (m) with 1.13, the map has to re-load, and doesn't persist. When it does this, the game slows down noticeably. The more I open the map, the slower it gets. I've got a video of it starting to happen here: https://www.dropbox.com/s/1792d8wsid9do32/2020-08-19 21-25-08.mkv?dl=0
If I never open the world map, the game is just fine. I don't remember this behavior happening with 1.12. (It didn't re-render like that.)