Need advice - large throughput drops when downloading large files (single threaded only) - via ethernet

[g67575]

I've formatted and re-installed Win11 on the internal drive, all drivers setup.

It's appears to be functioning normally now :

The above is at default settings (except for side scaling which seems to cause issues sometimes. Power saving settings off also).

I can make it even smoother by using this command:
netsh interface tcp set global autotuninglevel=restricted

setting autotuninglevel=highlyrestricted

seems to give the best overall results when it comes to TCP retransmission. At least, according to Mlab's speed test:

 

[Felon]

setting autotuninglevel=highlyrestricted

Yeah so that’s the tcp scale factor. Normally when tcp “windows up” the window size grows by a certain amount, tweaking that will enable the scale factor to go bigger, (so the server transmits more bytes in a window)

This is useful on links with higher latency and can give better throughput in some scenarios.

We use things like this on high capacity links (terabits per second) to optimise TCP transport, otherwise you end up with no throughput

 

[g67575]

I think I finally figured out the cause of the problem.

I have just re-enabled 'compress this drive to save disk space' on my C drive, which is something I did with my last windows 11 install as well.

This can save quite a lot of space on a 2TB drive, and at the moment I'm only using a single SSD.

After the compression process completed, downloading now looked like this again:

I managed to reverse the effect by simply disabling compression on the user folder on C, which is where I typically download files too (specifically to the desktop).

I will think twice before enabling disk compression in the future...