mylatex – Make a format containing a document's preamble

The file my­la­tex.ltx per­mits you to cre­ate a for­mat that pre-loads a set of pack­age files (and/or other macros) that you reg­u­larly use. In some cir­cum­stances, this can be a great ad­van­tage (though on an or­di­nar­ily fast mod­ern com­puter on the desk­top, gains will be lim­ited).
The gen­eral scheme is to ini­tialise your us­age by a com­mand of the form:la­tex -ini my­la­tex.ltx whick will cre­ate a for­mat file my­la­tex.fmt, which you then use as:la­tex -fmt=my­la­tex