The problem is that with that many discounts, nop is going through each discount and every discount requirement every time a page loads so it crashes your site. The only solution for me was to modify the Nop source to assign an ACL to a discount and bypass the user role discount rule. This filtered out all but a few discounts and sped the site back up.
See here: https://www.nopcommerce.com/boards/t/41594/feature-request-acl-on-discounts.aspx