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‘grep()’, ‘sub()’, ‘regexp’ and variants work considerably faster for long factors with few levels. (Thanks to Michael Chirico's PR#18063.)
The change to the internal table in R 4.0.4 for ‘iswprint’ has been reverted: it contained some errors in printability of ‘East Asian’ characters.
For packages using ‘LazyData’, ‘R CMD build’ ignored the ‘--resave-data’ option and the ‘BuildResaveData’ field of the ‘DESCRIPTION’ file (in R versions 4.0.0 to 4.0.4).