dosbox version?
Tried the various output= settings in your dosbox config file?

Yes, I already tried ddraw, opengl, openglnb, surface, overlay and I also changed machine= to many settings, but sadly nothing seems to get better. However I noticed that this slowdown is not specific to DOSBox, I tested WinQuake and many other non 3D-accellerated games, It happens the same --slow like a pentium 100 with cheap PCI display card. And not only games, even DOS Apps. (Neopaint, SEAL2, etc.) are also very slow.

By the way thanks for suggestion, wd. I think that if this happens to every GF9 user then it's a horrible news for DOS game lovers -- anyone buy Geforce 9+ just to play 3D Hardcored games and must completely forget DOS and Windows retro games?

DOSBox version: 0.72

For anyone read this topic:-
If you use DOSBox and are about to buy SB Live!, Audigy or X-fi then don't hesitate; these sound cards support Soundfont, with it you have a really beautiful music in DOS game that supports General MIDI
both in DOSBox and VDMSound. I myself downloaded many free SF2 and mix them together to my own version 164 Mb soundfont; the result is in DOSBox I got a greatest music device that I can never get in real hardware.

I tested WinQuake and many other non 3D-accellerated games, It happens the same

Strange.

Try upgrading your graphics card drivers and use output=opengl or ddraw
when testing stuff, and keep an eye on the dosbox console window if there's
some error message/hint.

OK. wd, I didn't upgrade the driver yet, but you remind me of it's relation to the problem. I tried turning off every eyecandies in nVidia's 3D settings and then output=opengl in DOSBox (ddraw doesn't help much, it's 2D mode); the performance of DOSBox improves (about 30%, I think). This is not yet the exact solution but I think It's better than nothing. It's obvious now that the slowdown is not specific to DOSBox, It's global to my system and do you know what have I found? when I turned off Vertical sync. in 3D settings, the performace in Winquake also improves. This is most strange, It means that there is also vertical sync. signal waiting in DDraw with GF9 cards (I borrowed GF9600GSO from someone for testing, the result is the same to 9800GT) and it implies that GF9 cards have no real 2D mode but instead the 3D without eyecandy emulating 2D (can anyone explain this in better way?).

And for the real DOS session, there seems to be no way to change any card's settings (there is surely no control panel in DOS, nVDia discontinued support to it for years), or the VGABIOS flashing helps, I don't know.

By the way your suggestion give me the sideway, wd. I will use output=opengl to solve the slowdown, thanks.

Geforces were always weak with real-time palette changes in 8-bit color. It isn't just the 9 series affected by this. It also happens to GF2 and it has done this for years, SDL or not. 24/32-bit accellerated output modes such as opengl in dosbox will get around this palette speed issue.
ATI doesn't have this issue, though it does have a palette color ramp precision issue in SDL (when in 8-bit color. screenshots can't capture this problem)

This is a pretty common complaint with various Doom ports as well; as far as I've seen, the only permanent solution has been "don't buy NVIDIA"

It also happens to GF2 and it has done this for years

Yeah, I once used Geforce 5700 and experienced this slowdown as well, but that time I thought it's because my system speed; But in real DOS it seems fast enough, I don't know what's going on with newer geforce VESA BIOS or what version is it, 1.x, 2.0 or 3.0.

as far as I've seen, the only permanent solution has been "don't buy NVIDIA"

Next time I won't. 😜

You could try to convince the DOSBox devs to translate the 8bpp to 16bpp for output as CVS versions do in vgaonly mode 😉

Interesting, but how?

Yeh that's been on my mind, supporting the direct 8bpp modes is more trouble than it's worth in speed for most people with the changes detection

This might help... I know sometimes if you just run the driver setup for your GPU with out completely uninstalling it your current one first, might cause confilicts. I read this in several forums before. Every time I get a new driver version, I uninstall the current one in Device Manager and reboot, then I install the new driver. Never had any conflicts or FPS issues since. This mainly helped me in the FPS department. But this helped me with Windows games. I never noticed any diffrence from my 6800gt to my 8800GTX in reguards to DOSBox for speed or problems. So hopefully it might help. Never know.

MikeRS wrote:

This is a pretty common complaint with various Doom ports as well; as far as I've seen, the only permanent solution has been "don't buy NVIDIA"

I'm still really confused over this because I have ZERO problem with this sort of thing on an XFX GeForce 8800 GTX. Have never had issues with palette changes on my old 7900 GS, my FX 5200, or my Ti4200. So I don't see what could be different between all of these cards and the ones you guys are using.

I agree with wildweasel, I had no poblems with my 6800gt or my 8800gtx. And my friend runs all the setting I have but uses a 200 series card.