Just Cause 2 PC Mini Tweak Guide:
There are a lot of settings in Just cause 2 and initially it can be difficult to figure out which ones are best left disable if you feel you could do with some extra performance. Below I have listed a set of tweaks that I recommend performing one at a time (in order) until you reach a level of performance you're happy with.
The PC version of Just Cause 2 is really well optimised and will actually run really well on hardware as modest as a 2ghz Core 2 Duo + 8600GT + 2GB RAM while still boasting some really nice graphics
but it does have a number of advanced settings which can bog down performance on lower end systems.
Turn off the Nvidia exclusive effects
: Bokeh filter and especially enhanced water can have a devastating effect on your framerate and their quality benefit is questionable. Enhanced water does
look nice but sadly it seems to chop around a 1/3 off most people's framerates at all times, even when there's no water on screen at all. Probably only worth it for GTX 295, 470 and 480 users.
Use D3DOverrider to enable triple buffering
: If you're not a fan of tearing then this is just a no brainer. You will
get hitching in busy scenarios otherwise, even on very powerful hardware. This advice can be used for any number of PC games as well. Details on how to do this are here.
: Its a nice effect and all but it does eat performance and the overall effect is pretty subtle. If you want some extra performance, this is one of the first things you should consider turning off. If you do like the effect then I'd recommend just using the "low" setting, higher settings will cost more performance but even at low quality the SSAO implementation works well. Fwiw, the console versions don't support SSAO at all.
Set object detail to medium/low
: By default the consoles only have this set at low and yet very few people have complained about the popin as its masked by the depth of field very well. You'll probably only really notice the benefits of the "high" setting when base jumping so setting this to medium is a nice way to get back some performance
Set shadows to medium but leave "high res shadows" selected
: This will produce some very nice shadows but the performance impact won't be so great. What you lose is the soft shadowing effect which softens shadow edges with a sort of dithering pattern. Personally, I think it looks really good but it does come with a pretty harsh performance penalty and I know for a fact some won't find the resultant effect desirable. If you're on a very low end system (say a 9600GT or below) you may want to disable high res shadows as well.
Set AA to 2Xmsaa
: Due to the heavy use of depth of field and low colour contrast present in most scenes, you'll start to see seriously diminishing returns past the 2xmsaa setting so this is a great way to claw back an awful lot of performance.
Consider using a 30fps cap
: Honestly, I personally don't feel like this is a game that demands
a locked 60fps, especially if you're playing on a pad, so the option to lock the framerate at 30fps is well worth considering. Follow the "commandline customisation" link in the op for details of how to do this.
Consider using a lower resolution and enabling GPU scaling in your drivers:
As the texture detail in this game isn't very high at all, the benefits from higher resolutions aren't quite as high as they are in some other games. So dropping down the resolution and letting your GPU scale the image won't have the dramatic effect on the visuals as it might in other games.
If you're still having difficulty maintaining a decent framerate then consider using similar settings to the console versions. Details on the equivalent PC settings are listed in this post