Do you see those metal mask structures that create plasma spheres that destroy all enemies when you touch them? There are 2 kinds. The ones that look like machines and the ones that have smiling faces. Shoot the ones that have faces to create a Plasma Sphere. Don't touch it until the white part of the sphere vanishes. Now touch it. You'll be instantly warped to the next level. Most levels have at least one. However, they're commonly placed in high speed areas or behind the mask ones.