Lower latency on Three when uploading

I spotted an interesting phenomenon today. The latency on my Three connection drops when I'm uploading large amounts of data (specifically when running an upload portion of a speed test).

When idle the latency on my connection is usually between 40 and 50ms (as tested by pinging 158.152.1.65, an IP address old Demon customers might recognise). It settles down at around 60ms when the downstream is loaded.

However, during the upload portion of speed tests (where just the upstream is loaded), the latency drops to 25-30ms. I basically never see that low a level of the the connection is idle (idle including general background traffic from a houseful of devices).

Shame I can't get that level of latency normally...

The TBB speed test doesn't see this reduced latency in its timings though, it records 60-80ms for the upload portion (though at the same time pings show the latency at some level at least has dropped).

Post deleted by RobertoS