lolwut since when brah "champion" >_>
On topic, it's probably a *wee* bit faster than 1.5-min execution. For my attempt(s) at Nationals, I averaged about 1:15 per cube for memo (I was constantly looking at the timer to pace myself), but with all the later refreshing, I think it adds up to about 2 minutes per cube. Doing the math for the execution time should give 1:15-ish per cube.
That said, all this is without any practice or even a "formal" method. Imagine what someone with enough dedication (and time) could do. I do feel like 40 is very attainable.