After updating my iMac (late 2013) to OS X 10.10.3, my cursor has begun to move very sluggishly and erratically. In addition, my Apple Wireless Keyboard and Magic Mouse both randomly drop their connection entirely, often taking minutes to reconnect. The keyboard will also occasionally send repeated keystrokes to the computer, continuing until I physically turn it off. I have tried to restart the computer (many times), reset the SMC and NVRAM, boot into Safe Mode, and turn Bluetooth, WiFi, and the peripherals on and off, all to no avail. Several times the machine would boot without any lag, only to begin lagging when I opened Messages or Safari. There is no Bluetooth interference, as none of my other nearby devices experience any Bluetooth issues. I have also noticed that USB peripherals work perfectly, without any lag.
Are there any potential workarounds I haven't tried? Or will I simply have to cope until Apple pushes another release?
Update: These issues, to a lesser extent, are still present in OS X 10.10.4.
Best Answer
If you boot into safe mode, does the erratic behavior persist? (i.e. use the Mac in that mode for hours if possible as opposed to using it to rebuild some system caches and then reboot back into normal boot state)
If you make a new user account, does the erratic behavior persist?
Can you reproduce the keyboard issues in recovery HD and/or single user mode?
Those are the first things I'd test to see if a workaround is possible. Also, get a
sudo sysdiagnoseevery time the OS is laggy - those logs will help if you need to open a bug report with Apple. I've not heard of (nor experienced first hand) problems, but it's also soon in the release cycle.