You need dash to be able to do this, but what you have to do is (I did this on controller, but it is probobly possible on keyboard and mouse) put your finger on the jump button, then slide it over to the dash button in quick succession, then repeat. If you get the timing right, you can go quite fast

This has already been known for quite a while now and longer categories use it a lot, its called "double dash" it's not used in any% and most other categories because dash is skipped in them

Oh ok, I don't do speed running for this game so I didn't know.