In LOCERF 08-2 (GOYA made it), the mission file was ~260kb. Without the ~70 planes with wpts added, The file was ~120kb. So you see, just the aircraft themself represent 140kbs of the file. Now you cant have a LOCERF without SAMs, Ground targets etc. :) However, you're also saying that that one was more stable anyway , and as far as I know, this one was not much larger in size. I try to make em small as well, but often you cant cut on SAMs or aircraft...
I agree on the scenes thing though. Alot (not all) of the drops and lag is often client based.