I can play Skyrim on high settings easily with plenty of mods too, but with FO4 I can only run low and it gets quite choppy in populated areas/multi-enemy battles.

Does anyone know of a fix for this other than upgrading since currently it's not feasible for me?

Waiting for optimizations and/or upgrading the video card are your choices from what I can tell. My old rig couldn't handle F4, so I upgraded multiple parts including a R9 380 4gb card. I've been able to play on medium with 55+ FPS. I could play on high (the game itself suggests ultra) but it starts to dip into the 30 fps or lower doing that.

GPU seems the biggest factor for fps re: upgrades (if your original CPU isn't a total toaster, I mean). My 1st gen i7-920 @stock 2.67ghz does just fine maxed out (despite being 6 years old) when paired with a 980ti, for example.

What are your specs...depending on hardware it's possible there's just not that much to do, unfortunately, if you already have a lot of settings on lowest. You could mess with settings via the .ini files, but haven't seen anything much that would increase fps by a whole lot vs. just the "lowest" default game settings.

how long has it been since you formatted and reinstalled windows? the game runs fine for me at 1440p 90fps capped. Hell it ran fine at 120hz but it CTD more than it does now. My PC is more than capable but it runs anything ive thrown at it. Seriously, after some time your system becomes clogged with useless stuff. If it has been a while i would just reformat and do a fresh install of windows, install steam and your drivers and try it out.

Plus the game will be optimized. Skyrim was the same, FO3/NV and pretty much every game made will be optimized. We dont live in the game in a cartridge age anymore.

Also try changing to Win 8.1 or 10 if you're running 7 or older. The new systems run new games a bit better than the old ones. (And its a free upgrade.)

Thanks for the replies guys, and I should have posted my specs, sorry.

AMD Phenom II X6 11000T 3.31 GHz

16 Gb Ram

AMD Radeon HD 6800

Win 8 64 bit

It's been since I built this rig years ago, but have never had an issue before.

On a lower end of the hardware spectrum, my R9-270X is doing High+ decently. Chugs a big in very heavy spots, but 95% of the time it seems fine. (disclaimer: I'm not one of the "60fps or death!" folks. I thought Skyrim was fine at 40.... )

Oh, and everything I have is at the speed it came. No overclocking.

edit: I think FO4's hardware detection is a bit silly, though. When I first ran it, it suggested Ultra. I thought that sounded crazy, given that my system is a lot closer to the minimum specs than it is to recommended, so I just went with High.

Running W 8.1 64 bit