Different cars behave differently with TC on, but the the higher you set the TC the less power it will put to the wheels, this is because TC is primarily to stop the wheels spinning. This means you have less power off the line and less power comming out of the corners but the car will stay regular and is very difficult to spin, but can cause understeer, with no TC you get the max amount of power available all the time and it's up to you to control it with the throttle, in FWD cars if you simply go for the POWER approach you will get alot of smoke from the tyres ad carry on in a straight line (understeer) in a RWD car you will get the opposite and will find yourself doing doughnuts.
TC is good for begginers but your laptimes will suffer.
Take TC off and practice it's worth it in the long run!
Hope this helps.