volume buttons have delay, any help?

Try resetting PRAM

http://support.apple.com/kb/ht1379

I have had this problem for quite a while now. After having tried all of the suggested fixes such as resetting PRAM and numerous others I have encountered on these forums, I have found that, in my specific case, the problem is caused by a popular third-party program, Boom.

Boom preprocesses and boosts sounds you play on your MacBook. Disabling boom solved the problem for me (which I didn't have under Mountain Lion).

Hope this helps.

Problem occured on a MacBook Pro (13-inch Retina). OSX Mavericks 10.9, i5 2.5Ghz, 8GB RAM.

If you have BOOM that's the problem, quit the app and you'll see, i've already mailed the company about this issue, the told me they were working on it (:

Hope it helped >.<'

Thank you so much

I reset my pram and everything is working perfectly

Thanks again