Just did some testing with texture pop in in the area called Midtown mall (since it was near my spawn point and has a lot of store signs which seem like notable offenders of pop in)
Uncapped FPS (well, 144 since that's my monitor) = pretty much never popped in while I was standing there. Ended test after 30 seconds or so.
Basic forced 30 FPS Ini cap = 4-5 seconds. Still looked kinda bad but at least popped up.
Edited Ini to 60, cap via Rivatuner to 30 = textures not popping for a good 15 seconds at least, some of them popped but not all of them.
So, basically, at least on my end, you can't edit the ini's FPS at all, even if you cap it via other sources, if you want even semi-acceptable pop in.
Really hope they fix this, because even the best option is still pretty shitty at times.