Installed TDU on Windows 7 32-bit. The game runs, but when you drive, every few seconds the game freezes and then continues. In the "freeze" time the car keeps traveling in a straight line and constant speed. In other words when the freeze is over you might find your car off road or against a tree or building. Totally unplayable, will never be able to complete a race.
Running TDU with patch 1.66 on a AMD Athlon X2 6000+ with 4Gb RAM and a nVidia 9800GT with 512MB video RAM. Mobo is Asus M4N78.
Game works fine on XP.
Running Farcry 2, GTA 4, CnC 3 amongst other games with no problems. Have all the latest drivers an updates installed.
The symptoms you've described don't sound like CPU issues IMHO. Easy thing to check, run Task Manager, play the game, then check Task Manager as soon as you experience issues - was the CPU graph pegged at 100% for the period you were having issues?
Haven't got TDU I'm afraid so cannot give an answer with backup, but I do have one question: What are you using to control the game - keyboard, gamepad, steering wheel? Sounds like a weird issue so hoping it's down to a dodgy W7 driver for a steering wheel as if this is using keyboard I'm stumped.