Seems like Big Sur does not process well

Playing the new season game after the upgrade to Big Sur, the performance of Class has been very bad. The movement of Class is slow and not smooth, which means, I think, the processor of iMac does not well process the movement. So the Class movement is slowed in seconds. I feel dizzy watching on the screen during the game.

For example, Necromancer blew a corp, then it does not happen for nearly 10 seconds…but monsters around Necromancer are moving. Necromancer can run or jump but it cannot perform constantly well. Its movement is slow and delayed in seconds compared to the mouth click.

Same issue here. The game is playable if you click on max frame rate for both options and slide the bar to the lowest. Game will run the same, however, items will not paint/show up in inventory/stash/backpack and could take seconds/minutes to appear. Very frustrating