In case your game gets slow, it's always helpful to identify the parts of code that take up too much time to compute. This is how you can measure execution time:

local start = stat(1)
-- .... do some intensive stuff ....
printh("this took "..((stat(1)-start)*100).."% of a frame")

Hope it helps, and thanks to @Felice for pointing out how to accomplish this.

sulai