Guilty confession time: There were times where I killed either Abe or Munch in MO just because I didn't want to have to spend the time and energy to get them where I needed them to be. It was faster to kill them if there was an egg where I needed them to be...^_^;
You can complete one of the mid-game levels in less than 3 minutes by abusing this. (I don't remember the name, but at the start you have to cross a bridge right away to an area where there's a bounce powerup, and four native mudokons, and you need them to open a gate to the rest of the level).
The shortcut I was referring to in the final level - the screen just below the one you come out on when the countdown starts. Instead of falling down from that one to the next one, just run and jump to the far left. When you land, keep walking left, and you'll cut out a heap of time.
Also, one I found just before in Stockyard Return (the game crashes when you do this on the playstation version. Only do this on the PC version). The screen with the four bombs moving in an X shape, you can go down to the bottom area, and run and jump out to the left (DO NOT STOP RUNNING, OR YOU WILL FALL AND DIE). You'll land on the screen just below the one to the left. (That's the bit where the PS version crashes). If you have a spare rock, throw it away. Pick up two more, then proceed as normal. When you get to the four bombs and the portal, make a path with just one rock.
Where you come out, walk two steps to the left, then throw a rock so that it hits the grenade next to the lever. Immediately walk onto the screen to the left as soon as it hits. Walk back again, and trip the detectors by hanging off the side. Once the slig hits the bomb, jump down and pull the lever. Continue as normal(this saves time deactivating the bomb, which can be really hard). (I'm not sure if you can sneak/run past the slog, but try it)