Regarding these two test you have done:
The only difference between those two tests is the AA setting, 2xAA versus 4xAA and obviously there2560x1440 - 2 x AA at DSR 4.00x = 5120 x 2880 48 fps to 55 fps in urban areas. AA is bad.
Self test: 2560x1440 - 4 x AA at DSR 4.00x = 5120 x 2880 27 fps to 35 fps in urban areas. AA is not bad.
should be a difference. You say 2xAA IS BAD, but is it normally inferior to 4xAA?
Do the same test with your current setting, 2560x1440 with NO DSR, and check if there is approximately
the same magnitude of difference between 2xAA and 4xAA. Then report back here, please!