Well the only differences with running a DOS game within Win9x are speed (probably slower) and whether it will run at all. 😀

I would be really interested in doing some benchmarking, to see how much slower a bunch of DOS games run in DOS 6, 7, and inside Win95. Do you know how I could set up some tests like this please?

Nothing special comes to mind. You just run programs in each OS and bench away.

If the computer is fast enough or if the game isn't too resource-demanding then you probably won't notice any difference.

Win95 will take up some RAM but will provide virtual memory from its swapfile/pagefile on the disk, so if you're running with a small amount of RAM then you may get slowdowns due to pagefile thrashing.

Win9x (and even Win3.1) also use preemptive multitasking for DOS sessions running inside of Windows, so that other programs (including other DOS sessions) can run at the same time. This does mean that games may run slower if Windows is busy doing other things in the background, and more importantly the slowdowns may be intermittent.

In the mid-90s I played Daggerfall under Win95 on a Am486DX4-120 while running a DOS-based dialup BBS in the background and it was tolerable (although certainly not ideal). Chances are you have nothing to worry about.

I'm currently running Windows 95 with 1 stick of 64MB RAM. I just discovered that Doom (I'm using Ver 1.9 shareware) can be run with the -timedemo demo3 command line parameters, and inside Windows 95 this gives me approx 65 FPS. Rebooting to "pure" DOS 7, I get approx 68 FPS. I wonder if my Win95 score of 65 FPS would increase if I increased the system's RAM amount? (I'll have to dig about in my retro boxes to find some more!)

Not likely, unless you have a lot of stuff running in the background. Doom itself isn't very memory hungry and either is Win95.