Just to add to what I has returned has suggested, keep in mind that dynamic windows (ones you can see through) will slow things up too, as will open doors (always auto close them). IMHO The ticket to faster game play is to balance on that fine line between,
1. Small/tight area's - which work well for speed, but don't do much for the eyes.
Possible solution; Make good use of the small areas by taking advantage of faster game play i.e... add more Dynamic entities to make the smaller area's more interactive for the player. Add that eye candy!
2. Grand open area's - good eye candy, but hard on game play.
Possible solution; Here if you want bigger open area's, go easy on the Dynamic entities. You can still have eye candy, just make good use of Static entities and keep the bad guy/gals to a minimum. Also you can make a area look big when it's really not, by limiting the interaction and movement of the player. ie... allow the player outside, but only giving the player a short route to travel outdoors before he/she most re-enter a smaller area back indoors. (remember to have the doors auto close)
3. Tons of dynamic entities - makes for a lot of interaction, but kill's game play.
Possible solution; You can have them, but only when you've tightened everything else up. ie... a small area, with a low ploy count will grant you free game speed you can spend on player - game interaction.
4. Lack of dynamic entities - takes away the fun factor (interaction), but aid's in game play.
Possible solution; this is the opposite of #3, here you can get over this hump, by laying out a good use of Static entities. ie... say you want a stack of crate's that the player needs to move to get to a door behind them, well make your stack out of a split between Static and Dynamic crates. Not every crate needs to move just the ones needed to pass do.
5. Mass amounts of bad guys/gals - after all this is what we want Action, but again down goes the game play.
Possible solution; This is the same as #1 smaller areas allow for more interaction. Make the player fight his/her way through a maze of rooms fighting Bad guy/gal's all the way. You also have control of when they spawn, all the bad guy/gals don't need to be loaded at the start.
6. Limited bad guys/gals - well helps game play, but takes away some action.
Possible solution; 3 parts to this:
a. Placement - one enemy in a good spot can be harder than 5 enemies in the open.
b. Spawn - as I said above you don't need every bad guy/gal to spawn at the start of the every level.
c. Layout - when designing a level, I find it best to build my area/room around the enemy that the player will encounter there, not just build a area and toss in some bad guys/gals after.
Regards
Mark
Surfin' The Apocalypse