I have no problem with other maps, with all I have usually 50-60fps. But when I get matched to abadoned complex, its fine until I rotate towards that Saturn like planet on skybox, fps drops down to 20 that makes me very easy target due to slower turning. Workaround is avoiding flying outside and stay near wall inside complex.
GF 540m (laptop)
6 gigs of ram
Some Dual core laptop Pentium processor.
Gfx settings al set to Low. Even invasion maps gives more fps that this.