OS X slow after switching users

I have a 2010 MacBook Pro running OS X Yosemite with 4GB of RAM and 200+ GB of disk space. After switching users, the user who has just logged in is slow. Waiting several minutes or dropping to Terminal and running sudo killall -u $other_user -KILL seems to immediately show an improvement in performance. The only consistent symptom I can find is that the other user has a number of processes, nearly all Chrome, using CPU cycles. I have not tracked this observation consistently enough to say if it is always true or not. When OS X switches users does it treat the other user as if the system were asleep or does it allow that users processes to run? Killing another users running processes is poor manners. Is there a better way to solve this problem? What can I examine to determine why the system is slow after switching users?