The test compares two different methods to concatenate strings to see which is faster. (the letters here are represented in random 2 digit ascii values) method 1: stores number string inside a variable, for each concatenation, 2 entries of ascii characters are concatenated together to form 1 digit and concatenate it into the string variable. method 2: treat number string as list of characters, the computed list are grown before being copied from the copied template. for each iteration, values are directly replaced to the new computed list from the looked up template list. result: method 2 are 0.1-0.2 times faster than method 1. it does not make big differences when being run in a compiled scratch environment. click the green flag to test it for yourself.