For many of you, it’s probably a bit too late, but if you’re a Mac gamer who uses Valve’s Steam for Mac games delivery client, you might want to hold off updating to 10.6.4: according to Valve, 10.6.4 introduces some major performance issues to owners running Macs with NVIDIA GPUs.
The following message warend Steam users who logged in over the weekend about the upgrade:
The recent 10.6.4 update from Apple has noticeable performance issues for NVidia graphic chip owners running high performance games. If you wish to avoid this, you should consider waiting to install the 10.6.4 update until Apple has had the opportunity to address this issue. Full details of what is contained in the 10.6.4 update can be found here: https://support.apple.com/kb/HT4150. If you have already installed this update and believe your graphic performance is affected, please contact Apple support (https://www.apple.com/support/) for details on what to do.
I haven’t noticed anything on my 27-inch Core 2 Duo iMac, but your mileage may well vary. If you haven’t updated to 10.6.4 yet, and if your Team Fortress 2 performance is more important to you than your Snow Leopard importance, it can’t hurt to hold off for now.