Apologies for bumping this old topic, but I found very little discussion of Dietmar Meschede's tools in relation to DOSBox performance here or anywhere else.

I got the latest versions of both S3 VBE/Core 2.0 and S3 Speed Up from the Wayback Machine copy of the author's site.

I've ran some tests with resource-demanding FPS games, most thoroughly with Duke Nukem 3D and Descent (both shareware versions for simplicity's sake). I have used the current vanilla DOSBox build v0.74-3 and the old build by Gulikoza with the FPS counter, like the OP here as it seems.

I kept most DOSBox settings in both instances at default, except for cycles which I capped with the limit function at 26800 (~486*) and 77000 (~Pentium*). Aspect ratio correction is on.

* -- as per the table on this page

With mode 13h speed-up (VGA+), so far I'm only noticing a slight increase in Gulikoza's FPS ticks (of up to about +4) in Descent when running at max 77000 cycles (for testing, I recorded a short demo of the first level and run it at various settings). At 26800 cycle limit there seems to be no tangible framerate improvement with S3 Speed Up.

I also tested the VGA+ mode with the demo of The Elder Scrolls: Daggerfall (which is known for very uneven frame rate), again at 26800 cycles there was no notable improvement as far as Gulikoza's FPS counter goes.

With Duke3D, there's additionally a built-in frame counter that can be turned on with the DNRATE cheat code. Also things get a bit more complicated here because for the 320x200 resolution, Duke can run in mode 13h, VESA mode 150h, and by editing the configuration file, you can also get an "S3 optimized" mode which indeed seems to be slightly faster in DOSBox even without S3 VBE/Core 2.0 and Speed Up.

For the VESA speed up (VESA+) of Duke's regular VESA 320x200 mode, the slight increase is again only noticeable when running at max 77000 cycles. Gulikoza's counter does not go above 70 FPS, but seems to stay near or at that mark more consistently with S3 Speed Up on (here I recorded a demo as well). The results are largely similar with mode 13h, i.e. no notable performance increase with the Speed Up tool.

Maybe I'm doing something wrong here? Perhaps I should've loaded an external VESA driver first?

UPD: I realised that DN3D is apparently using linear framebuffer VESA modes while S3 Speed Up is for banked mode. I grabbed the NOLFB utility from Ken Silverman's Build page, hopefully it will make a difference this time.

So I decided to take a more serious, systematic approach to testing.

I've used Duke Nukem 3D shareware v1.3D and DOSBox v0.74-3. Set the cycles to max and core to normal, configured the game to use no sound or music, and run at 320x200 mode. Then I edited DUKE3D.CFG for the following configurations:

• Chained - 0 [VGA 13h]
• Vesa 2.0 - 1 [VESA 150h]
• Screen Buffered - 2 (default "Normal Mode") [VGA 13h]
• S3 optimized - 5 [VGA 13h]

I would load the first level using the command prompt:

1dos32a duke3d /v1 /l1 /s3

Once the level started, I would type DNRATE and then quit to title to watch the first demo. The framerate ticker would still be displayed once activated.

To test VGA 13h modes, I would load S3VBE20 and S3SPDUP with VGA+ parameter. To test the VESA mode, I would first turn off LFB by using Ken Silverman's NOLFB.

According to my observations, it looks like under these conditions, the screen buffered mode (2) would yield the highest frame rate, followed by S3 optimized (5), which looked on a par but sometimes slightly below, and then VESA 2.0 (1). Chained (0) has the lowest figures overall.

S3SPDUP appears to make a notable improvement to Mode 150h frame rate (around +4 or so frames on the ticker in some cases), both with and without running NOLFB first. However, the rate is still somewhat below what you can get with VGA 13h modes.

For VGA 13h modes, I hardly noticed any difference between running with or without S3SPDUP VGA+. Maybe slightly better in some scenes. I think it would produce something like +1 frame on the ticker for the S3 optimized mode (5).

So I guess this confirms that the utility has a positive effect in DOSBox, to a certain extent.