I actually have a very good computer too, so I don't see the problem. One of the weird things that happens is that it often starts off at 30fps without any problems and as I progress through a flight it keeps dropping until it reaches like 10fps. Also I think it's probably because of the aircraft that I use, for example last time I tried loading up the CLS A340-600 and even if I lowered all my display settings down it would just stay at 10-15fps.
Another problem I'm having is that I really don't have a lot of autogen and scenery. Both are set to extremely dense but it's still nearly nothing. And again, dropping the autogen to even the lowest doesn't increase my fps. Only changing the aircraft.
The addons I use are GEX, UTX, REX and a lot of airports by Aerosoft and UK2000.
Specs
i5-3570k overclocked to 4.2ghz
XFX 7950
8GB RAM
Windows 7 64bit
It's really annoying, especially since some videos on youtube with people of the same specs as me run everything fine and it looks better too