Just made level 8.5 last night playing. No lag at all. I have upgraded my Video Card since the first stress test so this time around I was able to crank every dial to max. It ran without a skip at my normal desktop resolution 1280x1024 85hz. There seemed to have been alot of changes since the last stress test. I am thoroughly enjoying it so far, it is indeed everything I had hoped for so far. I died a few times on that quest in the mountains near Senjin Village. I ended up having to walk from Razor Hill back to my body, which sucked. I should have known that quest is tough, most of the monsters were at or above my level at the time. I also found myself scrounging for every penny (copper) I could get as I often found myself running short at training time.
What race and class are you playing? You should probably take a trip north to Orgrimmar and pick up some tradeskills which benefit the class you are. Do not forget to get the gathering tools for that tradeskill. Enchanting and Tailoring don't require a gathering skill. You're going to be scrounging for every piece of copper and silver you can get for a while, and the tradeskills will likely help you make more money. Spend money to make money. Also, in Orgrimmar, there is an Auction House where you could probably get equipment for your level that is pretty good but might be expensive. You'll eventually be finding green items decently often and making some good bank.