OS: Windows 10, running the software in Windows XP SP3 compatability mode
CPU:Intel i5 3317-U
GPU: Intel HD 4000
RAM: 8 GB

Software stored in an SSD. I seem to be getting sub-30 fps, often dips in the low 15s whenever smoke, fire or other things pop up (enemy ground/air units, friendlies too). This goes down even more when I use the MFD to lock on to target.

IL-2 Sturmovik runs really smoothly on my system, so I'm baffled as to why the software runs so poorly here.

Just in case you're still having issues and still want to play the game - I've found that the issue is caused by the (what else?) Windows Game Explorer service, which frequently causes failures to run or other issues for old games.

The solution is simple, but a bit annoying. It's basically impossible to prevent Game Explorer from running permanently, but you can try starting the game from a frontend such as DxWnd, or do what I did.

I use a program called Process Explorer as a substitute to the regular Task Manager.
With this program, you can clearly see the rundll32.exe process that runs with the game, identified as the game explorer service.
Simply right-click that process, and click Suspend. The process will halt, but still register as running. Now kill the game process itself (it's prevented from working right by the glitched Game Explorer), and restart it. Since Game Explorer is registered as running already, it will not run again, and the game will continue running normally.

This works for all games that are often affected by failures to start and similar issues, like (in my case) Carmageddon II, Homeworld Emergence, Unreal Gold, and Total Annihilation.

Open up the eech.ini file with notepad or wordpad, located under "C:\GOG Games\Comanche vs Hokum\cohokum". Search for "Persistent Smoke" and change it's value to "0" without the quotes, then save the file and exit.

eechi.ini - Notepad

[Graphics and Textures]
persistent_smoke=0

Neither comments are a solution.

Does anyone have another suggestion?

Have you tried the mod?

I am having troubles with EEAH, and it seems that is not solved by the mod.

But the mod makes EECH much beter graphics wise :)
Thanks for the tip! (Bedankt!)

Maybe this thread can give you clues.
They say 32bit = 1 must be in eech.ini.

Actually someone has triple buffering enabled, in my experience this will hurt performance big time.

The issue is as follows,

install EEAH from original CD, do not patch it, use Version 1.2C.

Now put the Aphavoc.exe into DXWIND and voila, its super smooth and Hi Framerate. I also use all AA and Supersampling settings in NVidia Controll Settings. The only issue in the moment is a rotation of the Helicopter to the left, its not controllable jet, but im sure there is a solution too...have fun!

Issue I'm having is there is no eechi.ini file with EEAH that I can see. I've looked all over the system folders for this game with GOG and I'm not finding anything. Game has in the garbage frame rate when facing terrain of any kind.