same problem when in cities or just looking into.
my system: Intel Core i7 2700k @ 3.5GHz
i get around 40 fps outside of cities but in citys 17-19.
when in wilderness my gpu load is at 99% and cpu load about ~ 40% per core
when in cities my gpu load is at ~ 49% and CPU0 64%, CPU1 5%, CPU2 32% CPU3 0%, CPU4 61% and 5,6,7 0%.
i tried to lower different settings but a lot of them do not change my fps in cities. i tested this in chapaevsk on a street (055,127) looking east. the ONLY 3 settings that actually improved fps were object quality, AA and shadows. after lowering object quality from very high to low i gained 11 fps (lowering to very low 2 fps more). disabling shadows only 2fps. disabling AA 3 fps. all other settings did nothing in the city. changing PP, ATOC and AO settings do only affect my fps when in wilderness.
i recognized when lowering object quality to low my gpu load went up from 49% to 60%.
also when setting this setting to medium or higher the windows of some of the sykscraper buildings began to flicker extremely. when at low they still flicker but not that much.
there were 30/30 person on the server and it was daytime.