Would there be a down side to setting default CPU affinity to keep all processes off of CPU0? Would there be any processes you would explicitly not want that done to?
We do not recommend such global rules, they can cause problems with some system processes, or at least we had one report of such years ago. Otherwise, they should do fine.
Instead of saying 'keep all processes off core 0', it's better to say 'keep all my heavy applications off core 0' and maybe some CPU intensive system processes. Just try to limit this in scope to something other than '*' [everything].