Frame rates per sec. seem to be of concern to some. Mine are "locked at 25 frs".
Should I be deliriously happy or feeling suicidal, ie adjust or leave well alone?  ???   

Windows 98 SE
Pentium III, 600MHz
384MB SDRAM 100MHz
nVidia TNT M64 32MB 2X AGP Video Card

Film, cartoons and things like that are showen at 24fps so if you can get 25fps then your fine. When it gets to about 12 you can start thinking... "Is it me or is the screen flickering?)

Don't go by what the framerate is locked at. If you look at what the actual framerate is, by pressing Shift-Z a couple of times, when you're on the ground with medium AI traffic moving around you. You'll see the framerate go up and down, in relation to what's on your screen. If you're getting around 20-25, in that situation, then you're doing very well.

Frame rates will decrease when you're in a busy situation, at an airport, but will increase when you're, zipping along at cruise altitude. Simply because there's less the system has to draw and display on your screen. Also, some aircraft and panels are fairly graphic intensive. So they could lower you framerates, too.

I think even if you're only getting 15 f.p.s., or so, the framerate will still seem fairly smooth, and your eyes won't be able to detect any "jumpyness", (really old word that I just made up). But when you land at an airport that has AI traffic, you would certainly see a noticeable difference/decrease.

Hope this helps.