If you run with a lot of AI, if you have any DXT3 textures that don't have an alpha channel you will get stuttering.
Even a single texture will cause a stutter.
Try the airports without an AI at all and see if you get smooth performance.
Then try with the AI on, if you get stuttering only with AI on then that is possibly the problem.
The way to check if there is an alpha channel present is to open the texture in imagetool and it will tell you.
Just an option possibly I've been stuck in this hell before myself - it was only with the help of FS-GS that I got a wonderful, smooth sim.
But this was a serious cause of trouble for me, and adding the alpha to a few textures that were missing one, solved the issue.
*********EDIT*********
Interesting, just browsing through my FSDT KLAS texture folder and lo and behold a bunch of DXT3 textures with no alpha channel.
Bingo - say hello to stutters.
Offending files found so far:
KLAS_FINGER.bmp
KLAS_roof_01.bmp
KLAS_roof_02.bmp
KLAS_roof_03.bmp
KLAS_roof_04.bmp
All the KLAS_ED_ textures
You can check for yourself by opening these files in imagetool and you will see on the panel on the right side it says "Alpha: None"
To add an alpha channel to a texture simply open it in DXTBMP (Freeware by Martin Wright) and save it again. DXTBMP will add a white alpha to the texture. If you look at the same texture again in imagetool it will now say "Alpha: Alpha"
Looks like KFLL is the same too
I can see the next hour is going to be spent resaving textures from my FSDT folder.
