The contents of the file preload.cfg can control the preloading of
commonly used fonts. Preloading fonts speeds up the processing of
documents but, because fonts cannot be `unloaded', you should not
preload too many; otherwise you may be unable to process documents
requiring unusual font families.
The default file preload.ltx is produced from preload.dtx. It
loads only a few fonts and these are a good choice if you normally use
documents at the default, 10pt, size. If you normally use 11pt
or 12pt then the time for LaTeX to startup may be noticeably
decreased if you preload the corresponding fonts for the sizes you
use. Similarly, if you normally use a different font family, for
example Times Roman (ptm) then you may want to preload fonts in this
family rather than the default Computer Modern fonts.