I'm playing the first Quest for Glory, and I'm already ready to quit. I don't know if it's a bug or if the game is just this slow, but it seems to take far too long for time to pass. I do not have the patience to wander around aimlessly for what feels like an hour until nightfall again. Is there any way to make time move faster? This is killing the game for me.

Can't recall for sure, but did you try writing "wait"? I know that later games had the option of you waiting for 10 minutes (as long as your stamina was low enough), not sure if it also happened in the first one.
The alternative would be increasing the rate of animations (+ button), then just switching between two screens to pass the time.

You can also rest to regain health, take a look at the manual, it tells you the command for it.

Resting will pass a bit of time as well as restore health, stamina, and magic points. If you have a strong need to pass the time, I think climbing the mountain to Erasmus's house advances one major time unit (midday -> afternoon -> evening, ...). However, it also costs stamina every trip.

Ah, the Erasmus hike is a nice trick! Also, I didn't know simply going between screens makes time progress. I was walking across entire screens, going for distance. If going back and forth can help, I'll do that.

I've already been resting, but usually he only wants to do it once before he's too impatient to continue.

I think this is what the message is when your stamina is too high. The threshold should be either half or max stamina, so throw some rocks or climb some trees (depending on class). Casting a few spells could also work, but mana will deplete much faster than stamina.

Hands down, the fastest way is to go into the tavern and anger the Goon (type "ask about guild" next to him). It passes time, and with three angers, it is night. Just don't get killed. You can do two angers with each class without dying, but the third usually kills most new characters. You can head over to the castle and work at the stables, also, to pass a significant period of time.

Here is a link to my speedrun where I do this. Happy gaming. https://www.youtube.com/watch?v=FvQB4vFFPTY