It's https://sourceforge.net/p/scintilla/feature-requests/1312/, here is the implementation for Notepad2
https://github.com/zufuliu/notepad2/blob/main/scintilla/lexlib/WordList.cxx#...
The one I was talking about was
https://sourceforge.net/p/scintilla/bugs/1734/
I don't completely agree with Neil's argument regarding optimization of short lists (which IMO doesn't require any optimization and is fast enough by itself) but it's not up to me to decide.
Anyway, we don't have any terrible performance problems with this - I was just mentioning it as an extra argument for possible typename colorization disable switch.