[–] PMYA 1 points (+1|-0) Edited

This is outdated as of a few days ago. Rather than clipping into the wall, it has been discovered that clipping through two blocks near that wall in a specific way, entering the first pixel of the pipe, with perfect movement in the warp zone area can save another frame rule.

It is unlikely that anyone will be doing it for a while though. The new record has a slow 8-4, so it is not necessary to save any more frame rules to get a new record. There are two remaining frame rules to save that are considered to be human viable. The one in 4-2, and a fast accel at the start of 8-1 combined with a flagpole glitch at the end, but it has only been done once with the use of save states.

Edit: Beyond that, the game may be reaching its limit in terms of time saves if nothing new is discovered. People working on the TAS are one frame away from saving an extra frame rule in 1-1, but nobody knows where that frame is going to come from.