WindowServer Bookend log messages
I cannot describe how terribly annoying this was for me post Yosemite install as well. Your beloved mac would freeze as hundreds (thousands?) of log lines detailing gesture bookends would demand intense resources. Anyhow, here is the secret sauce.

Note that multi-monitor preferences are going to be lost (screen arrangement, preferred display, etc)

Step 1: move/backup your plist files

sudo mv /Library/Preferences/com.apple.windowserver.plist ~/Desktop/
sudo mv ~/Library/Preferences/ByHost/com.apple.windowserver* ~/Desktop/


Step 2: Shutdown your mac

Step 3: Reset pram

press/hold Command+Option+P+R and press power button once
wait for two tones 
let go of the keys and allow your mac to boot normally


I hope it does the trick for you.