Have any DMs here ever pre-rolled results for combat before? I've heard it can speed things up but seems like something that gets you thrown into a middle-circle of tabletop hell.
But otherwise, do you guys have any tricks to stop sessions from grinding to a halt because a single combat encounter can take an hour or more to resolve? Or maybe that isn't even a problem for your PCs because you're Rico Sauvé the DM and every second of your sessions are totally enthralling and/or because this 5E.txt problems.
I've never pre-rolled combat as far as I know, but I have pre-rolled things before, which could have included combat. Basically writing down a list of results on a page and crossing them out as I used them. It kinda worked, but I stopped doing it, so I assume it was a wash.
As for tricks, I have far worse. Not rolling at all. Just making up the result I think would be most appropriate. Ignoring health, AC, and DC is another trick. If the player rolls high, he makes it, rolls low, he doesn't. This is handy if I want a specific outcome. "Oh, you rolled 19? The DC was 20, you just fail it." or "18AC boss. No one rolls more than 5 for the entire combat. Someone finally rolls a 12, it hits and that's the bosses' AC now." "The fight is starting to drag? The next hit on each enemy happens to be the last."
I also do the thing I've heard with different names like floating clues. Basically, you have a list of things you want the PCs to learn or discover that isn't tied to a specific location. Drop them in when needed. Iirc I got some criticism here when I mentioned it years ago, but it's a handy trick to know to keep the game flowing. My favourite example is the PCs are trying to solve a murder, and they should find a receipt from the waxwork museum in the victims possessions. It doesn't matter if the PCs search his coat pocket, his desk, the waste paper bin, or his cars glove box, they find the receipt, provided it makes logical sense.