The WR is currently just under 2 minutes but when you add up the individual-level record times the proven fastest in-game time can be 68.300 seconds. But we have to account for the jump out animation at the end of each level. Each of the animation times is exactly 3 seconds, though with 60 fps it jumps to 3.017 (This adds about .2 seconds to the total time) There are 45 seconds of extra animations but the last one isn't counted by the clock as the timer stops when you hit the last chest. This brings it down to 42 seconds of animation. Now with the possible best time of 68.3 in-game seconds, added to the 42 animation seconds, we have a 9.08-second improvement over the current WR. I do believe that the individual levels could be optimized for maybe a second or two time save overall (besides level 2, 6, and maybe 1) but I'm not going to make any assumptions.

To sum it up, the individual level bests add up to 68.3 seconds. The in-game animations take up 42 seconds of time. A 60 FPS framerate adds .2 seconds to the animations. So assuming that all of the levels are completely optimized as of Nov 10th, 2020...

The best possible time for the full game is 110.500 seconds (1 minute and 50.5 seconds)