Turn signal speed are different

What causes the left side turn signals to blink faster than the right side and what is the fix?

Do you have aftermarket turns or have you dont anything to the turn signals??? If not, it sounds like there may be a short in the wiring somewere. It wont be a fuse, otherwise they wouldnt be working, so it sounds like a short or something.
 
You can use inline resistors to control the variation of speed.

when i installed my alarm system in mine - i forgot one of my back turn signal's wires (i forgot to connect it) so my right side signal would blink 5 times per second were my left would only blink 1-2 per second. Dont know if you did any mods or not.

did you use different bulbs if they've been replaced (either by you or previous owner)? that may cause a drop in one side's amperage draw than the other.

Or you just have a bulb out.