Thanks for the reply, in answer to your points:
1. We've had the high latency issue today and the CPU hasn't spiked. It's at 2% so I think the CPU may be a red herring.
2. The issue seems to occur when there is increased load on the firewall. It returns to normal once it's rebooted, and then slowly creeps up again after an hour or so of use again. I've cleared sessions and arp and it made no difference.
3. As above, the CPU hasn't spiked today
4. As above.
I'm going to try a new firewall tomorrow from a different manufacturer that has gigabit interfaces and was released this year, rather than in 2008 or whenever the Netscreen 50 came out. I'm convinced it just can't handle increased traffic anymore.
