I just upgraded my Vigor 2926 to firmware 3.9.3.1 and found that my Virgin Media internet speed maxed out at 250Mbps. I restored firmware 3.9.1.4 and the speed is back at 540Mbps. Is anyone aware of an issue with the latest firmware on this device?

I also noticed that the CPU usage in the router is pretty much maxed out during the speediest on the latest firmware but only gets to 2 or 3% with the older firmware.

The 2926 only does 400Mbps top according their comparison chart so either you firewall was disabled or their product comparison is out of date. The only ones that can handle grater than 500 is the 3900 and 3910