Both systems are going to run at the same speed unless you're running some REALLY heavy processing or you aren't frame-locking your main loop with VSYNC. It's really not difficult until you get into the territory of making a program that runs slower on o3ds to feel like the same game.
This code runs the same speed on both systems, because it's framelocked.
ACLS VSYNC WHILE #TRUE ?"AYY" VSYNC WEND