Ranting Deleted...I like the game now...
Dave Baumann of Beyond3D said:ATI users might want to use the following command for areas of HL2 that are graphics limited (this might work with CS:S as well):
The command enables Z fill geometry pass in order to speed up rendering of the full scene rendering pass - by default I'm told it is disabled for ATI as they had some slight performance drops in the more CPU limited levels, however there are gains to be had in graphics limited levels.
AFAIK this is presently a default option for NVIDIA (the testing was done back with 9800 / FX's), but should be updated as the default for both in the future.
In the HL2 config file, Steam\SteamApps\<<userid>>\half-life 2\hl2\config\config.cfg, ensure that sound preloading is enabled with: