Here's a couple glitches I discovered a while back when chasing my sub-9:
Left Wall Glitch
When dropping a weapon (staff or blaster), it has a period of time where it flashes and cannot be picked up. If thrown leftwards, it is able to clip into walls. When a weapon is clipped into a wall, it rises up until it hits either the top of the level or a higher floor. This glitch can be used to get weapon in places that they otherwise could not be brought, as one cannot double-jump or wall climb with a weapon. However, it is not yet known to save time anywhere.
I got right-wall glitch once or twice, but only with dozens of attempts. It seems likely that is is close to pixel-perfect. Unfortunately, I don't have any footage of it. This may be more useful in saving time by allowing you to get a weapon into the arena quickly.
Weapon in arena
There is an invisible barrier when entering the Doof arena where the player looses control of Perry and the cutscene starts. If you attempt to bring a weapon across this barrier, you will loose it.. However, you can drop a weapon right before the barrier to have it cross the barrier, and then pick it up during the cutscene. Note that you will need to wait for it to finish flashing so that it can be picked back up. This is because you cannot go back far enough during the fight to get to it, even using out of arena glitches. This lost time would likely offset most or all of the time gained, so it would be necessary to get a weapon to that spot while loosing minimal time. This is not currently known to be possible, especially in levels 2 and 3 where it would be much more useful than level 1. Therefore, this does not currently save time. However, if it was possible to reliably get a right-wall glitch, it would likely save time in level 3, as the additional wait timer would run out earlier and not cause additional delay, and the difference in routing would not cost as much time as it would save.