There's quite a few short-cuts, speedrun glitches, and strategies. This page is here to guide you through them.
NONE OF THE SHORT CUTS OR GLITCHES WORK ON DS OR GBA
Part 1) Strategies
1) Stay on the inside of corners, this allows you to go through them faster.
2) Depending on how you play, you may want to use different karts because each kart has it's own stats.
3) Find out where the short cuts are, this will allow you to cut lots of time and be vastly in the lead.
Part 2) Short cuts
1) In Cerbur, the the part of the map shown has a small canyon in it, this allows you to skip a very small portion of the map.
2) In Venusia, the skating rink has a secondary exit on the left that lets you cut out an insane chunk on the map.
3) In Venusia, the part of the map shown has a little hole that shoots you across a canyon.
Part 3) Speedrun glitches
1) In Cerbur, in the part of the map shown, your can jump through the side of the volcano to die and spawn inside of there, this cuts the map in half.
2) In Bo-Bong, you can jump inside of a tree in th part of the map shown. Once inside of this tree you can drive on leaves. If you do large donuts on the leaves, it will count those as laps.
3) In Zarong, you can jump to the other road in the part of the map shown. This cuts out the entire map.