I hated it at first but I love it now. I usually use one of two options available to me, both are satisfying in their own way...
1) The simple option, just use a bit of power and say goodbye. I joined a roundabout in front of a 106 cruise last weekend, just driving at my normal pace I was well away from them in seconds without even breaking the NSL limit, despite the fact they were clearly trying to "keep up". Far from racing it was the safest thing to do by a long way as they were driving like they didnt fancy living much longer.
2) Just say sod it and slow right down, especially if they are stuck to your back bumper. This has two potential outcomes, a well educated boy racer will often stay right behind, knowing that your car could be off in the distance within seconds if you wanted to, even though they would usually immediately pass a car going 30 or so in a 40. Alternatively they will get frustrated as anything and eventually overtake. You need to be confortable with yourself to do this, but if it means they get to go online and say they wasted a 172 Cup in their 1.1 Corsa, well, someone will knowingly laugh at them eventually...