Firefox often times out when accessing paypal.com and other sites that use certificates from DigiCert. The same sites can be accessed reliably, from the same computer at the same time, using chromium-based browsers. The problem goes away if I disable the check to query OCSP responder, which may indicate the cause of the problem. Often the sites can be accessed after restarting firefox, but after a few tries the problem recurs. This is not a solution as PayPal is often accessed in the last steps of an online purchase.