Thanks. I'm glad you enjoyed it. Maybe I could add an options page in the future. You could turn the "metronome" off for the speed run version. The idea behind the metronome is it forces you to have to hold the numbers in your working memory a little longer, and empty them at a prescribed rate, which I think take a little more concentration. But turning off the metronome and going for speed would be a fun option.
Viewing post in Working Memory jam comments
I figured that the delay was intentional to challenge the players ability to hold longer and longer sequences in memory for longer times. I just found myself always pressing keys before I was allowed to and it started to feel a little bothersome after a while. Don't feel that my comments warrant changes to your design, it's good how it is :-)