I just played through SQ1-3 without any technical problems, but now that I'm playing SQ4, there's tremendous lag whenever a screen loads or when I call up the save menu. I haven't changed any DOSBox configuration settings ... should I?

I'm running Windows 7 64-bit.

I'd set the output to something like ddraw

Thanks for the suggestion. I tried that, but it still has the same lag as when I used the default of overlay.

Changing the cycles value in the cpu section from "auto" to "max" seems to have helped. Hopefully that doesn't introduce other problems.

EDIT: cycles=max did introduce a loss of some sound effects and made a timing-based puzzle impossible. cycles=20000 seems to be working pretty well. The delay in changing screens and in popping up the save screen is still noticeable, but is much better than when I was using cycles=auto. I noticed a similar issue in SQ5, so I'll try that value there as well.

You could just download ScummVM (http://www.scummvm.org) and use it to play the game.

ScummVM will fix plenty of Space Quest 4 bugs as well and timer related issues shouldn't occur.