Printer is pausing when the pressure advance is changed (Marlin M900 Gcode). Printing with a constant value causes a seam gap. (MK4S)

I usually print high layer heights (0.25mm+) with PETG which gives flow rates varying from 2mm^(3)/s to 18mm^(3)/s through the print.

I found that I was getting large gaps in the seams of my prints like this from 3dprinting.stackexchange.com. The problem was occurring at the start of a line, not the end.

After a lot of investigation I learned how to correctly set up the "Adaptive Pressure Advance" feature in orcaslicer and eventually solved the seam gaps and problems with first layer adhesion.

However, I recently (since spring 2026) noticed some problems with the prints being quite slow and defects on the outside of the print. Upon further inspection, I have realised that the printhead is pausing every time the pressure advance changes. When I created a test print which deliberately uses the M900 command after every move for a short section. The printhead only pauses for a few milliseconds, but it's enough to result in bulges at those points. https://i.ibb.co/fdmTbNC1/image.png

I created a github issue but I didn't get any response - I really need help to solve this problem as the prints are just too weak without adaptive pressure advance, but this new problem slows everything down and makes them ugly.

Has anyone else used Adaptive Pressure Advance and seen these slowdowns? Which firmware version are you running? I have the latest (March 2026) firmware on my MMU3 and MK4S.