I have my system set to suspend BOINC activity when certain high memory and high CPU applications are running, including occasional gaming. Just now I tried to launch a game and my system lagged severely. On investigation I discovered that while the BOINC client said it had suspended all running work the actual tasks themselves (rebound_boinc_5) were still running.
I run a custom install of BOINC to manage where it saves work data so the number of disk writes do not chew up my SSDs and would rather not have to completely shut down the client to play the odd game due to poorly behaved applications.