"Poor" Usenet speeds on VM

So I've used Usenet for a very long time, and in all that time, it's been one of the few things able to saturate a reasonably fast connection.

Looking back at my logs from when I was on Hyperoptic, the average speed was 30-35MB/s - so it should be more than capable of saturating my VM200 connection with 20 connections.

Yet the most I ever seem to get is an average of around 7-8MB/s - bare in mind most of these happen in the middle of the night, too!

When running TBB speed test, I nearly always see over 100mbps on single thread and 200+ on x6.

Are VM throttling Usenet or is something else going on here?