There are 3 main techs anyone that wants to speedrun this game should know: Fast lasagna, Air Jumping, and Damage Boost.

Fast Lasagna, named after the first use found in level 1, is a technique in which a platform that can be jumped through is jumped into and then by tapping left then right on the d-pad, garfield is positioned on top of the platform that was being jumped through. This is used most often in level 1, but it can be used in level 6 to save jumps, and therefore time.

Air Jumping is simply taking advantage of the coyote time most developers put into platformers. Whenever garfield isn't in his "falling" animation, you can jump. This is used primarily to save time in levels 4 and 14 to save around 10 seconds each.

Damage Boost is just what it sounds like, but it isn't used in the platforming levels of the game. Instead, when i refer to damage boosting in this game, i am referring to level 2 and level 5. in these 2 levels, when you are held up behind the screen, you rocket forward with speeds unable to be achieved otherwise. Level 2 uses this easiest, and level 5 has a glitch that lets garfield get stuck in a hill, saving a second.

That is unfortunately, all known tech for this game.