I have previously reported this problem and have followed advice to remove addons / switch off addon upodates, do clean install etc. all to no avail The only addons are ABP and Avira AV Safe Browsing (recently added, the problem long pre-dates that). The problem is occurring on rel 53 and rel 52esr (which I am currently running due to needing access to a specific silverlight-based legacy site). I have collected a netmon trace which demonstrates the issue, but I have no idea of the significance of any of FF's non-http requests. It has been generated from a desktop shortcut that simply loads FF, with a specified url. It takes ten seconds from FF's first network request until it executes the GET for the specified page. Why is there such a long delay? With IE, the GET is almost instantaneous - but I really don't want to go there :-) I can supply a copy of the trace (.cap) or just headers as .txt but can't upload them from here. System is 64 bit running Windows 7 SP1 HP