I realize there are post dealing with all these issues, just tough i would add my two cents.

Running a Mac Pro with :

Processor 2,66 GHz Quad-Core Intel Xeon
Memory 16 GB 1066 MHz DDR3 ECC
Graphics ATI Radeon HD 4870 512 MB
Software OS X 10.9 (13A603)

These issues were present while on OS X 10.8 as well

Issue 1 :

When tabbed out of the game the only indication I get for a match ready is a jumping icon the sound doesn't play anymore, I do have the setting turned off the hear normal game sounds when alt tabbed, I believe even with the settings as is the match making sound should still be active.

Issue 2 : I will occasionally get game freezes of a second or two during laning phases ( it happens through most of the game, but most relevant in laning as you can get caught out of position easier) where the hero keeps moving the the last clicked spot.

Issue Three : I've tried to realize if this is a combination of certain spells but happens too often with team fights once or twice every third game my game will crash as the majority of spells start being cast in big team battles. I just get a beachball and get dropped out of game.

If there is any info I can provide further please let me know, so I can see if I can get it to you.

Thanks for your time.