Nothing wrong with 30, or even 15 FPS with the Source engine !
Remember, it makes extensive use of the level of detail technology, which makes it draw only what's needed and save a lot on polygons. 30 FPS on this engine is roughly equivalent to 100 FPS on the HL1 engine. At this rate, I guess you can play, right ?
Remember, the human eye can't do captures at more than 15 Hertz, that with the Shannon law means that below 30FPS any flickering is not discernable ; and furthermore the human brain thinks at 10 hertz (i.e you can't take more than 10 ideas per second, be them chained or not). Hence the limit of playability with the source engine is 20 FPS. Skilled players and people with high reflexes may prefer a higher value, but requiring more than 30FPS is inhuman
