Why does Starcraft 2 get slower as a match progresses?

The problem is simple, I fear the solution is unobtainable.

Whenever I get (roughly) more than 120 supply my game comes to almost a complete standstill. Playing ladder makes me cry a little inside. I need it to not to lag at all. It's not the connection as playing campaign gives me the same problem. Currently all graphics are set to their very lowest.

My Rig:
Windows 7 b 64-bit
Intel core i7 3.5gh
16 GB of RAM (DDR3-2133 (G Skill RipjawsZ F3-17000CL9-4GBZH))
Radeon Dual-X R9 280x 3GB
448gb SSD Samsung
1000w PSU

I've overclocked a bit to get some extra juice out of this badboy. Sadly, in SC this makes no difference.

I can play any other game for fun, Thief is the newest one I've tried out all on maximum.

Running latest drivers and versions of everything.

Solution 1:

I had different but similar issue: problem was related to SSD drive.

See more details here in SC2 topic: Replays freeze/don't work after upgrading to Windows 8!

and in superuser site topic: https://superuser.com/questions/570416/ssd-works-slow-under-windows-8/746207#746207

Eventually, my claims to manufacturer was satisfied and I got credit for my SSD. I got around 60% of original price though.

I would recommend you to run diagnostic tool and if version confirmed - talk to manufacturer for replacement with another model/money back or store credit.