Has anyone noticed since installing Yosemite that audio played through a bluetooth device will start to lag behind actual Mac activity (e.g. volume changes) over time, and will steadily get worse? The problem seems to be exacerbated by doing other tasks on the Mac while the bluetooth connection is active - browsing in Safari for instance. I have had up to 5 seconds of delay on occasion. Quite repeatably as well. The audio playback can be re-synchronised with what is on the computer by re-pairing the bluetooth connection, or simply changing audio output to internal speakers, and then back to bluetooth. That's a little annoying though! Have submitted as a bug to Apple, but wondered if anyone else had had a similar experience.