> luahbtex should behave better, right, if the font is loaded with the > harf renderer selected?
Ah, you seems right. But, when I added [RawFeature={mode=harf}] to the example given at the beginning of this report and processed the file with lualatex-dev in TeXLive 2019 of February 14, the memory comsumption was again mere 2GB... (I did it on last Saturday). {mode=harf} can possibly behave better as we do not observe the huge memory comsumption in xelatex, but I have personally not digged into that possiblitty as the lualatex-ja developer recommends not to use {mode=harf} with lualatex-ja as \paragraph{Using \LuaTeX-ja with LuaHB\TeX} Using \LuaTeX-ja with LuaHB\TeX (\LuaTeX\ integrated with \href{https://github.com/harfbuzz/harfbuzz}{HarfBuzz}) is not well tested. Maybe documents can typeset without an error, but with unwanted results (especially, vertical typesetting and \cs{CID}). Especially, \emph{We don't recommend defining a Japanese font with HarfBuzz}, by specifying \texttt{Renderer=Harfbuzz}~etc.\ (\Pkg{fontspec}) or~{mode=harf} (otherwise). at https://ja.osdn.net/projects/luatex-ja/scm/git/luatexja/blobs/master/doc/luatexja.dtx Best regards, Ryutaroh