MacBook Pro constantly freezing/pausing for fractions of a second

Solution 1:

EXACTLY that symptoms had my friend, he noticed it mostly in Excel an in the gaming - random freezing, first about a half second, later (1-2 months) became worse between 0,5-30 sec.

It was a HW problem. He bring his notebook to apple service, something (don't remember what) got changed and everything is OK now.

Solution 2:

I had the same problem. It was the motherboard. Check the serial, Apple did replace (for free) a whole bunch of boards because of a failure.

Solution 3:

Strange as it may sound, it could be the SSD. I have an OCZ Vertex 2 in my MacBookPro7,1 (2010 13") and I discovered that something in iStat Menus was causing disk I/O to stop for a few seconds every now and then. This would manifest itself not by completely freezing the system, but things like when launching apps the icon would bounce and bounce until the I/O resumed, and Chrome would refuse to open new tabs. I got around this by disabling the CPU and sensors widgets in iStat and I haven't had any problems, but there could be a similar app on your system that is causing the problem.