100% cpu load is normal when running any modern 3D game.
I run on board sound on a 3 Ghz AMD.
I suffer massive stutter and lag on 20+ aircraft take off CoOps with engine smoke and dust effects but this clears after about 1 min.
Tips for alow spec PC:
Run "msconfig.exe"
Shutdown all sevices that are not required.
Untick ALL startup proscess that you dont require for IL2
Quicktime,Realmedia,Skype,MSN,nero,photo,picasso,etc.etc.etc all start process' at start up .
After a while your PC hasto load 40 things at boot takeing 10mins for the hourglass to dissapear at boot upAND tacking up valueable memory.
you dont need them every time! If i want nero I'll click on its shortcut..... I dont want it running on the taskbar just in case I need it
Run a good spyware/malware remover.
If you are behind a NAT router think about that masive Norton/McAffee security suite taking up valueable resources. I have a Netgear router with NAT firewall and Windows firewall. With no problems.
Turn off your anti-virus auto-protect /realtime scan. Evertime you load/play scenery,sound effect etc.they are scaned for viruses. There is no need to do this all the time ,Turn it off while playing but dont forget to turn it back on while downloading that dodgy porn/ warez