If you reset the game as you kill the final guy, your next run will be entirely in slow-mo. And if you hold down the button for the grapple, you don't use it up. I used both of these to get a 1:09
EDIT: 1:04 with better routing
you can also press f12 to get the slo mo effect
Edit: I got 1:01 using the grapple glitch
Amazing! If you have a YT channel, post a video. I'd love to compare routes!