One thing I find interesting...no matter what the format of the game, the slowest parts are not usually combat so much as the sort of...directionless slogging around that parties do when they're exploring.
I've seen, in a realtime game, action stop for upwards of half an hour or MORE when the party comes to a fork in the road, or a door...or otherwise has choices about which way to go, or what to do.
No one wants to be responsible, I think, for the call that leads to disaster. No one wants to say, "Lets go left," and then find that 'left' leads to the trap/boss monster double whammy. Plus, unless there's a LOT of attention to detail and description, the "corridor crawl" is probably the most boring part of the game. Which you'd think would mean we'd want to rush through it...but in reality it means we want someone ELSE to rush through it.
One thing that helps a little is more input from the GM, even just in the form of descriptions. Going west, say, and having the GM go, "Okay, you're still in the ruined down, exits are southwest and north" is a bit less involving than something like, "Ancient, weathered buildings scroll past as you make your way, step by hot muggy step, farther into the vine-crusted ruined city. Looking around, you see no obvious buildings of interest in your immediate vicinity, though the street you're on curves to the southwest and there out of sight."
On the other hand, it's hard for a GM to get the energy to make big posts when no one else is. It is a vicious circle!
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In summary, what can I do to help?