Augmentarium

All Half-Life 2 games are totally playable in big resolution, no need for configuration files.

I get 18-50 FPS with next settings, also I use bigger resolution so if you want more FPS just lower resolution.
For all Half-Life 2 games set next options

OPTIONS > VIDEO

Resolution 1280x720
Aspect Ratio 16:9

ADVANCED

Model detail Medium
Water detail Simple reflections
Texture detail Medium
Shadow detail Low
Shader detail Low
Color Correction Enabled
Antialiasing mode None
Filtering mode Bilinear
Wait for vertical sync Disabled
Motion Blur Disabled
Multicore Rendering Enabled
High Dynamic Range None
Use 'bloom' effect when available Disabled
Windows Aero extensions available Disabled