Yah, I suppose because YMMV - seemed to help my mid-level vid card (GTS450) though :) Please report back if you try this, BTW, would like to know if it helps people!
All in-game aircraft use numerous LODs - 4 to 5 per plane in fact - and the 1st one is a high-poly model requiring a fair bit of processing power to render smoothly. So what folks with less-than-HAL9000-level setups can do is to replace the first 3 LODs with the 4th and presto - more frames! Here's how it's done with the Ka-50 for example:
1) Go to \Bazar\World\Shapes\
2) Find a file named ka-50_lod3.edm
3) Make 3 copies of the file
4) Rename the copies to ka-50.edm, ka-50_lod1.edm and ka-50_lod2.edm respectively
5) BACKUP THE ORIGINAL SIMILARLY NAMED FILES NOW IF YOU HAVEN'T DONE SO ALREADY
6) Replace the original ka-50.edm, ka-50_lod1.edm and ka-50_lod2.edm files with the copies you just made
+ rinse & repeat with other AC / objects if you want - should help even more. Cheers guys :)