[CorvusCrypto]

stuff like this can't help

var n = Double(arc4random_uniform(UInt32(weightTotal * 1000000.0))) / 1000000.0

[brothrock]

Yep totally, going to take another pass to try and make it faster. This was just a make it work experiment. Had a few fun troubles with random, but at the moment it just crawls :(.

[sdegutis]

Out of curiosity, what's wrong with that line? Why is it slow?

[CorvusCrypto]

starting from inside the arc4random call you have double float multiplication, then cast to uint32, then the arc4rand call, then the double cast for the uint32 result and then a double float division. this adds up in instructions.