Common applications eating your CPU and memory budget like a Cookie Monster, definitely.
I don’t use Adobe ARM, so I can’t comment on that, but it’s quite common to have services in the background doing very intrusive updates that kill the performance of even the strongest machine.
Hopefully your problems will be solved after that, but keep monitoring 
EDIT: If you only use Adobe to read PDF files using Acrobat, you can use Sumatra PDF instead, i’ts very compact, very fast, and uses almost no disk space at all