With my Battle of Britain mission sets, I'm getting upwards of 45-50 frames per second on a lower end and closer to 55-60 per second on a higher end. This is with:
-AnKors shaders and dll's
-HD clouds from WOFF
-WOFF scenery and terrains
-300+ ai airplanes
-2048 textures
-AnKors effects from the shaders
And so on. It really depends on your system that determines what you'll get for frame rates. With a really high end laptop, you can expect closer to 90 or 100, depending on your configuration settings.
From what it sounds like, you're getting not too bad of frame rates. I'll try some of my Battle of Britain missions over cities this weekend and let you know what I'm getting for frame rates.