Optimization using Allegro in C++

What's up /prog/,
I'm currently trying to write an rts/ shooter using C++ and allegro. By shooter/rts, I mean shooter in the terms of ikuraga, and rts in that you will be switching control of units as well as being able to "freeze" the area around the ship you are currently controlling and que some command for the flotilla you are commanding.
Seeing as I have this in mind, I need to be able to have at least 90 units in the game without visible slowdown, so if you have some suggestions, I'm open to anything.

Thanks!

Allegro and SDL are slow as fuck except for screen sizes 320*240 and below. Use opengl or directx instead.