I see we have some patches coming to the game in the next few months and thought I'd make a note here of how the game is currently performing on my system for later reference.
Location: Run around Propast in Book 1 (with max population out and about)
Settings: all maxed except no blur
1920x1080 windowed (on 1920x1200 screen)
CPU: AMD FX-8370 @ 4Ghz
RAM: 16Gb 1866 DDR3 8-9-9-24
GPU: XFX Radeon RX 480 @ 1288Ghz w/8Gb RAM
All at default settings, no overclocking
With Shadows at 25m FPS ranges from a low of 45 at specific areas to a max of 100+, average over much of the city around 60-70
With Shadows at 100m FPS ranges from a low of 25 at specific areas, to a max of 65ish, average over most of the city around 40-50
Tweaked other settings but clearly shadow distance had the biggest impact on FPS for me, all else being equal.
Tough spots including rounding the corner from The Hand That Feeds to look at the Collapse Memorial, and some segments in the crowded Chinese market.