While trying to increase page speeds load, it would make sense to use the google cdn.
now if your prestashop does not use ssl it is an easy change
just edit header.tpl
find
<script type="text/javascript" src="{$content_dir}js/jquery/jquery.easing.1.3.js"></script>
and change to
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></script>
now if your site is ssl secured its a bit more complicated, as you need the call to jquery to be supplied from an https source.
you could just call
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></script>
from every page, but an https call takes slightly longer than a straight http call
their are several ways you can achieve the desired results, mainly involving lost of {if} loops in the header to ensure the correct protocol is used
but a far easier way is as follows
edit init.php in you web root and add the following code after
