If someone pulls off P4 1P (which would be min rate) that would be slick, but I don't think it's happening due to how difficult it is to achieve the necessary lateral motion in time.  And P3 seems like it could maybe be done unrestricted but never in 4 height.

I pretty much exclusively worked backwards on this one, as you have to.  I did find that you could avoid all the problems of horizontal wrong-bonding by building an expanded form of the polymer that resembles tall-very-dark-thread-but-explosive, then doing some cool debond-rebond reshaping that may be a flavor of syrup.  In this form, the only issues to contend with are calcifier placement and lateral movement.  But, when I found solutions for these, they turned out to provide a cleaner and faster solution that didn't use the very-dark-thread intermediary at all.  To turn my solution here into that intermediary, move the rightmost bonder one tile to the left and get rid of the arm on the far right of the polymer.

In fact, feel free to remove the rightmost arm entirely when showing this on stream.  nonlooping is annoying but optimal as it saves 10 cycles here

Last day edit: managed to save 6 latency, 4 by reordering glyphs and 2 by taking inputs using a crazy track loop instead of a basic period 4 arm.  I still have pretty significant wrong-monomer woes but I don't see any way to do better on that front, need material to be in front of the polymer at the start and the crucial section cannot handle a smaller molecule substitue.