sorry for the late response
basically any map including the default ones some times, it helps if i enable sv_cheats 1 then do gmod_mcore_test 1 but that gives me like 10+ fps
If you have hardware that's better than my 2.7 GHz quad-core, my 6 GB GPU, and my 12 GB of RAM, but are getting way less frames than me, then you might have some internal computer problems, like hardware failure, overheating, and/or the insides being filled with dust, or maybe you have some junk on your computer that's slowing it down
For reference, at the spawn area in gm_construct, i get ~34 FPS, looking straight up i get ~77 FPS, and under the map i get ~135 FPS, and i play on max settings in borderless windowed mode