Some of the reasons may include but not limited to:
After every update of nVidia drivers, MOST if not all settings are reverted to defaults.
Infact, it is preferable to do a "Clean" install of nVidia drivers instead of updating.
Once a while, u need to delete Shadow Cache by first disabling/changing in nVidia Control "Shadow Cache Size"
then cleaning cache folder/sub-folders (best is "DDU" Direct Display Uninstaller)
and thereafter re-enable nVidia Control "Shadow Cache Size", just using default will do (as new drivers cache size is set at 4/5Gb)
I run 7 instances all the time. Once a single instance start acting up like quitting game or main playing account stutter or at worst
closing the game entirely, cleaning the cache is what I do. Works 100% all the time.
Good luck.
Can you explain how I clear that? I did notice that when no instances up my ram usage was running around 4-5GB