There's no denying the sims needs optimizing, but i run it just fine on a two year old PC:
Asus P6T deluxe motherboard
i7 920 @ 2.7Ghz
Ati 4890 1GB
normal hard drives (no SSD)
3GB or RAM (yes, only three)
win7 x64 Pro
My only problems in regards to usability is that some times loadouts go missing or the menus go funky but work fine the next time i fire it up. As for performance, the problem is not lack of it but that it's sometimes inconsistent.
All in all, i get nothing game-breaking after the latest beta patch, running 30-60 FPS with occasional dips to 25 and only split-second pauses the first time a certain texture loads (no more of the initial continuous stuttering) depending on amount of aircraft, clouds and the terrain i'm flying over.
So how do it do it? Well, i just don't expect to run everything on high with anything less than top of the line hardware, that's how
I run it at 1680x1050 with most settings on medium, model details and land shading on high, vsync on, shadows and roads on, SSAO off, AA off (since people say it doesn't work much anyway).
Sure, there's still room for improvement, lot's of it. At the same time though, a lot of complaints come from people who expect to run it maxed out on 1920x1080 or higher with hardware older than mine, that's not realistic and will probably never happen.
At the same time, too many people are obsessed with running it at the maximum possible settings, completely disregarding the fact that CoD on medium is slightly better than IL2 on max, they just see an option and want to max it out no matter what.
I've seen people with dual cores getting higher FPS than me, but most of it is probably due to my low RAM and them usually having nVidia GPUs of the same generation as my Ati 4890 or newer, more powerful GPUs of either brand.