I experienced lag here:
(Touched up to allow you guys to see it better)
Also, I'd halve the amount of particles in the burned-out room to reduce lag. It was fine a few seconds after I exited the sci's office, I presume that's when the particles stop being made or something.
I also noticed that the scientists at the console in the intro didn't have the "gag" flag set- might want to do that.
Another thing, could you PM me a basic synopsis of the game from the intro to the actual gameplay in the mod itself? I could suggest details, ideas, maybe write some lines for someone to record, or something. I'd really like to know how you're handling the half-hour in the lab before freeman gets there.
Finally, where did you download the enhanced textures? Can I get a link?
EDIT: You have at least a couple of PM's waiting for you, hotdog. Let me know if you guys need anything done that's within my skill set.