Thanks Nat, appreciate the response. I don't get to test with a gig ethernet connection very often but a few days ago I was able to and seemed to be getting 270 - 300mbps which is clearly an improvement. Why would it improve? Is it like ADSL where it takes a few days to maximise the speed?
I appreciate that I am not going to get 350Mbps all the time but I expect to get close to it most of the time.
I will try and get some more testing sone over the next few days and post results here.
My laptop struggles to reach full speed on www.speedtest.net, it seems to be related to the adverts as when using an adblocker it reaches full speed. I presume the numerous animated adverts are using up CPU/memory resources and preventing full speed.
Thanks cje85. I have been using the speedtest.net sight specifically as Virgin support say to use that one. I have tried others though, with similar results.
I would be surprised if anythng going on on your browser affects the speed test. I think the speedtest is essentially a "line" test between your device's network card and the test server, it merely reports the result in your browser. I could be wrong but that would seem the sensible way for it to work (like dropping down to MS-DOS and doing a ping or traceroute test).
Bottom line is these speeds are way short of what I am paying for (100's of Mbps short!), not just tweakable differences, or differences between test websites.
The speed test can be affected by other thing using system resources. If you monitor your CPU usage during the test it does increase so if there are animated adverts already using up CPU power it will affect the result of the tests, especially on laptops which generally have lower spec CPUs compared to desktops. That's why a simple test like www.fast.com is useful just to confirm the results.