Reduce your mental load to increase your speed: limit yourself to fewer additional stat blocks per encounter (e.g. if there is a boss battle with lair actions, you should ideally have 1, at most 2 additional monster stat blocks on top of that boss). Running something like 4 stat blocks is sufficient cognitive load that there is no way for you to play your monsters optimally and still be fast.
Reduce your reliance on small dice rolls to increase your speed: preroll a table of damage for any given statblock’s actions, so that you can dole it out quickly (still roll the to-hits live tho, in case of crits and misses and reactions, and have misses consume a line from the preroll table too).
Add a low-value off-turn minigame for players to play: I like to make knowledge checks free (History, Nature, Insight, etc). You could allow players the chance to each get 1 free knowledge check in per round, but only off turn. That way if it’s another player’s turn, and they are thinking for a while, you can have the other players roll their knowledge checks and tell you what they are looking for. Resolve them later, at the beginning of those PCs’ turns, which will also keep other players engaged since they are learning new info. Don’t let them ask tho, save it for when you want to provide the distraction.













Sounds like you wanted to interact with the GM’s world, while the GM wanted to write a book. You can’t make people value the things that you value: they have to choose to value them themselves, or they have to value you enough to make a change. And vice versa.
If uou cared about helping the GM write a super cool novel, you wouldn’t have broken the mould. If the GM cared about player choice, they wouldn’t have gotten pissy about you taking the plot off of their rails.
You have had this experience, but now you know not to play with this person anymore. Good riddance. Next time you have a session 0, you have a preference to probe. “Hey, GM, you’re not using a module or writing a book, are you? I’m hoping for some more fluid ad libbed interactions, rather than everything being preplanned.”