The L3 cache errata that you refer to is incredibly rare, particularly under normal computing conditions (never heard of it actually happening..ever). Not to burst the bub but I doubt the Phenom TLB errata is your problem.
The lookaside buffer can be turned off in the bios (top, in the advanced setting section, when bios is updated to most recent build) and in fact is set to "enabled" as a default in all newer bioses I know of. Talk to anyone with a Phenom and they will tell you to disable the TLB erratum in the bios or you will see the performance hit you are talking about. Any adverse affects of turning it off is, 99.9999% guarantee, not the TLB bug.
EDIT: Didn't see the part where you got the performance back w/out the checksum. Congrats