of course you should look at your startup scripts
to trim down on useless startup programs, like
sendmail is a classic, _most_ people dont need to
start up a mail server on a PC. You can even start
processes in the background on bootup, so that the
system does more than one thing at a time. but
you should always use the KISS method with things
that dont make much of a difference, like bootup
times

Of course you can change it, it's not
binary only, don't let freedom choke you too badly.