probably not.
Usually it's caused by either 24 bit graphics. (those are poplular under linux) and/or some audio daemon for your window manager).

Linux doesn't have 24-bit graphics at all. All X servers of the past few years use 32-bit when the user requests 24. It takes extra effort and some obscure options to enable true 24-bit graphics.

Priority has (almost) nothing to do with that as well, since if you run only one program, it will get the full CPU power no matter which priority it has.

A common cause of these things are indeed audio systems. Only recently has linux got a decent sound architecture (ALSA) with all capabilities you'd need. Which means there are many other ways of doing audio still around, and some behave better, some worse. My first guess would be that whatever sound driver your SDL uses, it is the culprit. export SDL_AUDIODRIVER=alsa and see if that works (better). Unfortunately, there's still mych work in progress, so it may not yet work for you, although the ALSA folks are getting better each day.

I was seeing the same problem as sehh (I'm also on Fedora Core 4 -- Personally, my sound is AC'97 and don't know what sound support got installed and used). The export SDL_AUDIODRIVER=alsa made a big improvement. Things went from being ridiculously out of sync (seemed like a couple seconds) to being just a minor annoyance (slightly worse than on my winxp setup).

Edit: I just tried running as root. Without setting SDL_AUDIODRIVER, the response is very quick.. but the sound crackles. With SDL_AUDIODRIVER=alsa, it works just the same as user -- noticeable latency, but good sound quality. Maybe I could adjust dosbox's sound settings to get good low latency sound as root.. but I won't since the alsa sound is alright and I'd rather run as user.

hmm i'll try running as root just to see if there is any difference...

You can also try and update ALSA to the latets version supported by your distribution. As I said, they had many improvements in the past year (mainly for users of onboard-sound).

I'm already using 1.0.10rc1 (1.0.10 final is the latest one) which is as new as it gets under Fedora Core 4. I'm also using a Sound Blaster Live! 5.1.

Based on my tests, games with have high latency (delays) in audio are games with heavy requirements or special needs. Not necessarily CPU requirements, i think its closely related to heavier emulation, since my cpu usage is very low while i see those audio delays.