I found that my Postscript files were taking an incredibly long time to generate and the file sizes were abnormally large. The problem was that, everytime I chose to set a font I would call ps_findfont() followed by ps_setfont().
It seems that every time ps_findfont() is called, the font gets embedded in the file. To prevent this, I keep an array of fonts I've already loaded, keyed by the font name. When I go to set the font, I first check this array to see if I've already loaded the font, and, if so, return the resource handle from that array. Otherwise, I call ps_findfont() and store the handle in the array.
Note that, if your call to ps_findfont() occurs while inside a page, the font will not be available on other pages. To get around this I just clear out the array at the end of each page.
My PS file went from 10 M to 75 K, and the time to create the file went from around 15 seconds to less than 1 second.