By movement speed do you mean.
step_size, fps, tick_lag and such?

You can locate fps and tick_lag under /world variables.

Did you write the code or is it someone else's? I ask because you seem unsure of your own design and that's...bad if designed by yourself. It also might be a sign that you didn't write the code yourself, but copy pasted from others. You're hurting yourself in terms of actually learning the language (and of course, ruining your design implementation).

Edit: To try to point you in the right direction of your question, take a look at these two links on movement delay.

Mob example (can change mob to atom/movable for both mobs and objs)
Client example

If you adjust the fps with a custom movement delay, you can get rid of the choppiness to a minimal and still appear smooth. I do 25 fps (PAL standard for video games) myself with a delay of 3 using something similar to what KaioChao uses for mobs/objs and what .screw uses for my HUDs (via client). Remember though, the higher the fps, the higher the tick_lag (fps/10, it's synonymous) can cause lag if overdone. Don't expect to go past 30 fps and be multiplayer. I know someone who uses 30 fps for his side scroller project and runs well in multiplayer, so going past this should not be needed.

Edit2: Oh, and you might want to look into pixel_step_size. I also use this in conjunction with my current setup at a value of 5 (try playing with this).