Parallels Desktop - Keys not working and serious input latency from their "fix". Help!

Hi all!

After updating to Big Sur, Parallels Desktop is as good as trash. There's a forum thread and a KB that they created on the issue, but I need an actual fix sooner than later, and I'm wondering if anyone has had any luck?

The "fix" they suggest for missing keys is:

From the menu bar click Parallels Desktop icon (II) > Preferences > Shortcuts, then select the VM in question and click the plus button to create the corresponding shortcut for the necessary symbol. Repeat for each symbol that cannot be typed.

But that only gets you so far. Since now the keys will work, but not when pressed consecutively, and sometimes not at all if pressed remotely close to the key-up event from a previous key.

Whenever there's any amount of repeated input from the mouse and keyboard Parallels will slow down and start dropping keys.

Has anyone found an actual fix for this instead of the hacky bullshit key mapping?

EDIT: Forgot to mention, that without their fix, the keys will work fine, with no input lag if you hold down the fn key, but not all keys work with that held down.