If your system is running slowly, perhaps a process is using too much CPU time and won't let other processes run smoothly. To find out which processes are taking up a lot of CPU time, you can use Apple's Activity Monitor.
The CPU pane shows how processes are affecting CPU (processor) activity:
http://stackoverflow.com/questions/24380159/corebluetooth-and-wifi-interference
http://lists.apple.com/archives/bluetooth-dev/2013/Aug/msg00023.html
This is a well known issue, and it has a solution that is confirmed to work for the Mac side.
sudo defaults write /Library/Preferences/com.apple.airport.bt.plist bluetoothCoexMgmt Hybrid
After you run this script, the issue will go away and BT connections will remain stable.