Hello - just for clarification, do you mean a single laptop or multiple ones w/ the same problem?
First, I'm assuming that a reboot did not help? Second, do you have BT (Bluetooth) activated & devices connected? If so, you might want to disable BT and turn off the devices - I've seen some discussion on the interaction of BT w/ Yosemite (possibly a bug?).
Finally, you might want to reset the SMC & PRAM - information HERE - good luck & let us know your results. Dave
Multiple laptops, though I don't understand how it would matter.
Reboot? You mean restarting? I went ahead and turned off bluetooth (BT). What do you mean about devices?
Resetting SMC? Checked link- looks complicated. I don't want to take the laptop apart.