Upload & Sell: Off
I am running Windows 7, 16gb ram, 240gb SSD on a 4 core 3.2 cpu, just build that thing in december, with 2 gb video card, so LR should be smoking and it was until I upgraded it to 4.3.
I was in the same boat. Noticeable slowdown. I deleted the preference file and now its back up to speed.