Hello,
unfortunately there seems to be an issue with the new Endpoint Security framework that File Shield needs to use on Big Sur; it manifests as a slowdown of resume for some users. We have reported it to Apple. We have also released a workaround in Avast 14.7 which should minimise chance of this issue occurring, however we are aware that it is not 100% effective. We are actively searching for an alternative workaround and hope for a fix of the underlying issue from the Apple's side.
We apologise for this issue
Kind regards,
Ondrej Kolacek