Looking for a good profiler for .NET these days I stumbled across JetBrain's dotTrace. Previously I had worked with the CLR Profiler, which did its job quite well, but after installing dotTrace...well...suffice to say I'd never go back again :). Using dotTrace is just soo easy and you can pinpoint performance bottlenecks almost immediately. Also it doesn't cause major slowdowns of the profiled app (as CLR Profiled did) and it has a quite nice UI too.
If you haven't tried it already, you can download a fully functional 10-day evaluation copy from JetBrains' site and give it a spin, maybe you'll fall in love with it as I did...