First of all I must say it is quite remarkable you are able to get this aged printer to print at all. You can adjust print settings to draft mode or, in this document provided by Adobe, a suggestion that you can try is:
If Adobe Acrobat Reader prints slowly try the following:
1. Open a PDF file
2. From the menu, select File > Print
3. From the dialog displayed, click on the Advanced button at the bottom
4. On the Advanced Print Setup dialog, make sure that “Let printer determine colors” is CHECKED.
5. Click OK and OK to print the document.
According to user reviews, it may also be the version of Adobe Reader you are using if this actually worked previously. There is an update available (click link for information on how to check for updates).
Lastly, there is a memory requirement to print .PDFs. That is based on available memory left in the printer.
Based on the product specifications, here is what I was able to find: