Long delays in connections through firewall

Hi all We have a FGT-60B which has suddenly started playing up. Firmware version is 3.00-b0668(MR6 patch 2) We use it for our general internet access and also for traffic to our hosted web site. Within the last 2 weeks, we' ve been experincing long delays (average around 30 seconds) when trying to browse to internet sites. Sometimes the site will come up after the delay and then be OK, sometimes it will load the page very slowly, sometimes you' d get an error saying the page could not be displayed. On our hosted site, customers have been reporting the same problems. I' ve traced the problem to communications across the firewall' s zones, by doing the following testing: Accessing our web server by it' s internal IP address (INT-->DMZ interface) and also by it' s public URL (the IP of which is on the WAN2 interface that is then routed to the DMZ interface so I assume INT>WAN2>DMZ). The DMZ only connectionis absolutely fine, but when browsing to the site using the public IP it is very slow. I assume that our general internet problems (internal -->WAN1) are caused by a similar interface-interface problem. We have limited reporting on the firewall, the memory and CPU usage is within tolerable limits, and really I don' t know what to do to troubleshoot this. I have of course rebooted the firewall and this has had no effect. Can anyone suggest what this might be or suggest some things to try? Thanks Andy