Forgive me if I'm being a thick git, but what do we do with it once we've downloaded?
When the file is downloaded and unzipped, you click on the .exe file within. It will ask to navigate to a program .exe file that you wish to modify so that it has 4 gig of memory available.
In the case of Sturmovik, navigate to your Sturmo directory and choose your il2fb.exe file. The 4gig mem mod will then change your il2fb.exe into an exe that will be able to access 4gig of memory. In practical terms that means Il-2 will work better and faster with less or no stuttering in game ...
I've tried this mod out and it works just fine.
Even though the mod automatically creates a backup of the original .exe, make your own copy just to be on the safe side.
And as an extra treat, it works for other programs too. If I have read the webpage correctly, it allows old 32 bit programs to access memory as if they were 64bit programs ... that's what i make of it and in any case, I've used it on several older programs of mine, old 32 bit programs that I still use and it works on those as well.
I modded my old graphics program, a 32 bit prog that I know well and do not wish to upgrade, with this mod and now it can apparently access 4gig of memory. In any case it does not crash when using huge graphic files anymore so i suppose the mod does what it promises ...
There is also a 1gig memory mod for il2,
https://www.sas1946.com/main/index.php/topic,2475.0.htmlwhich i would think is similar to this mod.
I can't say which is best, but I would be careful using both on one and the same .exe ... best to choose one of these mods ...