Scott Wasson from The Tech Report is on the ball - he benchmarked an AMD Phenom processor affected by the translation lookaside buffer (TLB) and L3 cache bug which is said to be rare but could cause system crashed under virtualization mode.
AMD promised a fix by way of a motherboard BIOS update but the sad news for AMD fans is that patch causes a penalty hit which Scott was kind enough to test.
Tech Report has all the detailed benchmarks here.
Across every test we ran, the difference between the Phenom 9600 with and without the TLB patch averages out to 19.8%. However, if we rule out the synthetic memory tests and consider only the application tests, that difference drops to 13.9%.
The most troubling results here are the applications where we see large performance drops with the TLB erratum workaround active, including the Firefox web browser and the picCOLOR image analysis tool. If one happens to spend a lot of time running an application whose memory access patterns don't mix well with the TLB patch, the result could prove frustrating. The BIOS-based workaround for the TLB erratum may achieve its intended result-system stability-but it comes at a pretty steep price in terms of performance.
Apparently motherboard makers will make the fix a kind of "feature" in their motherboard BIOS which can enabled or disabled. This makes much sense as the bug may not cause issues for some users.