Well, no highly detailed areas, no lush plant life, no moving objects, no ambient sound. I'm only comparing to Tomb Raider, which is the most recent game I've played, and runs fine on my hw.
Poly count is indeed low. I've also noticed the small number of lights, but forgot to mention. That's very good.
In the meanwhile I've disabled AA and Aniso filtering, but it only added a few FPS. I've also noticed that FPS is higher when standing still, which makes me think some parts of the rendering process are cached. Also, some lights can be set to shadowless or static, to improve performance. There is also the fact that the mapsize is 11, and complex (where I get more FPS) is mapsize 10, so I guess the sunlight needs a bigger shadowmap or something.
Also, it is indeed unclear what the map actually is. It's a mall with more beams and walls and less shops? Is it some sort of shopping + parkour centre? The skylights are nice, and the revolving door looks good too.
I agree with Suicizer that there is a lot of gray. The sunlight makes up for this, but after a while you probably get tired of all the gray. Maybe color each floor in 2 colors from a palette of 5-6 colors. Add your own textures.
As for the name, how about 'centre' (goes well with complex) or 'skylight/skylights'. 'shopping', 'mall', 'railings' (same idea as steelribs), iunno.