You can edit the snow.js with any type of editor.
PHP Code:
var num = 20; //Number of flakes
var timer = 75; //setTimeout speed. Varies on different comps
var enableinNS6 = 1 //Enable script in NS6/Mozilla? Snow animation could be slow in those browsers. (1=yes, 0=no).
The first two will let you change it, i changed it to 20/75, and it dropped to about 50% cpu usage for my members with bad computers. Keep tweaking with it and eventually it should work nicely for everyone, or you can turn it off with the last bit, for the mozilla users.