Not sure if it helps...but my game is all text right now.
Currently, it's about 1,039kb, 130,000+ words, and 600-650 pages long in word with 12 font.
I think Quest can handle up to like 20,000kb (20mb)?
viewtopic.php?f=10&t=5677^--- as mentioned here.
So .....without pictures or sounds, you could potentially make your game roughly 2,470,000 words. That's a lot of rooms and story! I imagine your game is lagging though because you are using the "map" grid feature. Try turning it off and making the directions in text more clear so that the player knows exactly where they are. Or you could reduce the spaces they travel. Maybe something like Flexible Survival does, "Go to areaname" and so on.