I would like to know an estimate on how much time the route @Meep_Moop used in his current PB saves over my PB. This would be very much appreciated!

I am not 100% sure on what you are asking. His time save would be your run minus his run. If you are asking for potential... Well only time will tell with better movement and practice of the route.

In terms of how much time, it's 13 seconds from subtracting the PBs? As for why, I think a huge part is that you go for the bottom left area first on your way down from the top left- this makes you pass through a waterfall more often than you need to (and it takes longer to grab the upgrade with 70 fuel vs 95 fuel). Most of the optimizations come from spending the least amount of time moving horizontally through water, like grabbing the bottom upgrade before the one in the sunlight at 25 fuel. Hope that makes sense!