Linux Steam rendering performance tanked after 1.5.5 update

[Daedalus1400]

System Info:
Linux Mint 20.3 Cinnamon
Kernel 5.4.0-122-generic
Intel core i7-6700K
32GB RAM
NVIDIA GeForce GTX 1080

Game Info:
1.5.5@prod@4e25bf4
Belts: 77270
Buildings: 42820

Problem:
After the 1.5.5 update, graphical performance dropped to unplayable frame rates. Dense parts of my map where I used to get over 30 FPS now achieve 4FPS, regardless of whether there are any items on belts. Even zooming in on empty areas to minimize the number of items on screen results in <25 FPS. Prior to a few days ago, this map had not been played since before 1.5.2 dropped. During the entire time I had the map loaded the tick rate never dropped below 60 UPS (~14 ms update time).

Steam does not allow downgrading to a previous version, so I cannot test whether the change in performance is due to version changes in the game or some change to my system.

When I use Mozilla Firefox to play the game, the very same map runs noticeably better, though still worse than when I was playing the steam version several months ago.

Starting a fresh save file also has the same issue, with a frame rate below 30 FPS despite there being no buildings or belts. Update time was below 0.1 ms.

All frame rates, update rates, and update times are taken from the in-game "F4" debug overlay.