Maya Bonus Tools has been organized to mimic the layout of the standard Maya menu sets. Each sub-menu contains a number of related tools. Each of these can be torn off and floated just like standard Maya menus. Note: Due to the close timing of the releases, this update to BonusTools is supported for both Maya 2019 and Maya 2020.
Here is a Python script that will create a little button in the top right corner to toggle on and off the thumbnails updates. Off course this script with work in the current Maya session and will need to be reloaded every time, or you can set it up so that it is loaded automatically at startup. this is the Python version: import maya.cmds as cmds