This will only add the command \MT@font to the list, not the actual font name (e.g. \T1/cmr/m/n/10), so that microtype will redo its font setup each and every time a font is loaded. This has been discovered by a user here: https://chat.stackexchange.com/transcript/message/52330126#52330126
I don't know why you need to patch these commands at all (the user's test document works fine for me if I just comment the patches), but in any case this is wrong.
Actually, I would also prefer to do any patches required in microtype itself, since for example these commands happen to change in the next version.
You can reach me at w.m.l at gmx.net to discuss this,
Hi,
in the latest patch to microtype, you've introduced a bug that results in exponentially slowing down compilation
\def\MT@register@font{%
}
(Likewise for the other commands. This change is in https://de.osdn.net/projects/luatex-ja/scm/git/luatexja/commits/26142dfa8cafe366a32dff1459c8f0f4c60c83d3)
This will only add the command \MT@font to the list, not the actual font name (e.g. \T1/cmr/m/n/10), so that microtype will redo its font setup each and every time a font is loaded. This has been discovered by a user here: https://chat.stackexchange.com/transcript/message/52330126#52330126
I don't know why you need to patch these commands at all (the user's test document works fine for me if I just comment the patches), but in any case this is wrong. Actually, I would also prefer to do any patches required in microtype itself, since for example these commands happen to change in the next version.
You can reach me at w.m.l at gmx.net to discuss this,
best,
Robert (microtype maintainer)