Bad performance on some maps?

Some maps drop FPS significantly, sometimes even lower than 60.
I’ve tried lowering graphical settings, but that doesn’t seem to do a thing.

I have Sapphire R9 270X TOXIC and AMD FX-6300 Black Edition. I don’t think such issues should exist, but they do.

The best example of that would be the map ttt_waterworld.

Vanilla maps run at over 200 FPS.

Other maps run from 70 minimum to 150 FPS on average.

Though, I’ve noticed that when pools close on ttt_waterworld (water and its reflection cannot be seen) the FPS jumps up by 15 to 25 even.

I find this really odd.

It’s probably the mapper’s fault. Bad optimization is the killer on many a map - eg rp_city2_v2. Would be a fantastic HL2 map if not for the fact that it lags when in the Nexus, or looking in the general direction of the Nexus.

It is the mappers fault, their failure to properly cut visleafs in order to break up visibility so the entire damn map doesnt render at the same time.