I will say here what i have said else where… I had major issues after 10.10 but it got a bit better when on the apple developer forums we figured out that some stuff was caused by permission issues that couldn’t be resolved while the OS was in use. We booted to the recovery partition (Turn off the machine. Then press the power button… once it starts to turn on hold down the option key till you see your boot drive options one should be your main system drive partition the other should say RecoveryHD or some such. Arrow key over to it then hit enter. Once booted and you are in. you will see a menu select disk utility and then select your MacintoshHD or whatever your normal Hard drive is named in the pane to the left. Then in the right side of the program do Repair permissions.
Then reboot back to your main system drive. see if that helps