On Windows a workaround is to set the folding process to 'below normal' or 'low' priority and see if that fixes Sublime performance. On Linux lower the nice priority. These settings simply force process-level priority, so you're not curtailing the amount of CPU power folding can use, you're simply backing it off in favour of anything else that needs CPU. Problems may be more noticeable on Linux because less aggressive GPU acceleration is leveraged overall than on Windows, at least in general on the desktop.
I ran Prime95 (which hammers all your CPU cores) and Sublime concurrently and saw no slowdown in Sublime whatsoever. That said, Prime95 defaults to a 'below normal' process priority as a default.
In situations where heavy constant CPU use and process competition is unavoidable, another workaround is to change the cursor from 'Phase' to normal flashing. It seems that the cursor phasing is done in software and is blocking, so if that struggles to get CPU cycles it will slow Sublime down as a whole.