I'm not sure how different Hyper-V is from KVM on Linux or a containerized solution, but that does sound low.
For comparison, I'm running Channels in a
systemd-nspawn container (think Docker or LXC). I'm using a roughly 5 year old processor (a Core i3-5010U) with 8GB RAM, no swap (think virtual memory or "page files" in Windows parlance) and Channels uses between 90–100% of a single processor when running
comskip with the default settings.
However, 1/8 is roughly ~12%, which may explain your usage. Since your Channels instance thinks there are 8 processors, and only a single processor is used with Channels' default settings, Windows may consider that as only 12% of 100%, rather than the 100% of 800% that many Linux resource displays would show.