Thanks for the well thought out reply!
Actually the effects was already set to 1, and indeed, it increases considerably the performance. As a matter of fact, the reason i set it to 1 was because of the big contrails of bombers (this happens of course when flying by 7000+ m of altitude), they costed a lot of fps. By altering to 1, there's a performance gain by almost 10 fps approximately.
Yes, SASEngineMod is enabled, though when disabled i don't see a difference really, and yes, its really a important feature.
Like i said, i noticed the big/core problem are not the amount of planes as i see it (i can enjoy playing with 30fps when many bomber are displayed), but rather the moment when the formation starts droping the bombs, thats the moment that fps drops to one digit number. I noted that once the bombs explodes/hit the target, the performance slowly starts to increase again, reaching the 30 fps mark again.
Not sure if the bombs dropped by those b-17's themselves (which you can imagine are very numerous on these 8th air force raids) are also very high poly and/or render in a demanding way, compared to vp modpack.
And i agree 100% with you on the performance of other modules. I flew already many missions on one of your DOF campaigns, and the performance is flawless, always constant 60 FPS! For sure, they don't have the same amount of planes of a big b-17 raid mission, but these aren't missions with "few" planes either. The same applies to Golden Age missions (though i didn't fly that much yet of the Spanish Civil War campaign, just 4 missions).
About the Jed Age module, i also think the performance loss wouldn't be a problem, since, as far as i know, post-50's air combat often involve way less number of fighters/bombers compared to the massive formations there was in ww2 (big focus on technology, efficiency, guided missiles, radars, less in production numbers).