I think this is 15:56 by frames, might be 15:57. Not sure!
I finished one casual run with deaths, then one run with turbo, and then it took me forever to get a deathless run with no turbo. A single mistake can take you out fast in this game!
Turbo doesn't help too much on most bosses, just a second or two here and there, but it can save a ton of time on the final bosses due to it allowing for triple or quadruple hits.