Differences in speed tests

Hi
When I run the BT Speedtester or speedtest.net or visualware.com, they show speeds around 70 - 77 down and 17 - 18 up. This on infinity 2.

When I do it on here it shows around 35 down and 12 up.

Doing a large file download from Microsoft (win 8 iso) or Linux Mint the throughtput is showing as approx 9M, yet the large file download from here shows at 2.7M

Why such differences ?

Thanks

Is the flash giving the same speeds as the java tester we have?

We show an average speed, rather than a burst which can account for the difference sometimes, add in that we do not use HTTP protocol to add another issue, and then an issue that some see Java running slowly after all the recent Java updates

The flash tester does seem to give different results, the upload is higher.

Clicking port 80 gives better download speeds.

If changing port improves speeds then suggestion is that ISP is managing traffic flow.