Sluggish speedtests

I have noticed on my Sky FTTP service when using a speedtest tool like fast, speedtest.net etc the download speed starts off sluggish, around 30/40Mbps for a few seconds and then ramps right up to 150Mbps.

Is there a reason for this?

It doesn't happen on the upload speed which is a constant 31Mbps from the off.

I used to get this on EE FTTC too - same router - Asus RT-AC68u.

I get the same ramp up over the first 2-3 seconds thing on SKY VDSL, for both download and upload. Truth be told I have always seen this for any speed test. I sort of think its someone in the "network saying...... here is another one, oh better get onto that now, wow that's fast".

the term is called https://en.wikipedia.org/wiki/TCP_congestion_control

Edited by iand (Sun 07-Feb-21 14:24:23)