Testing network speeds WITHOUT using HDD, on a restricted linux system -- curl only. Is this possible?

I got a weird one. I have two virtual hosts. I have limited toolsets as they are restricted vendor images that I can't go apt-get installing on. I want to test out the virtual networking on these, to compare them somewhat. One is a Hyper-V guest on a Dell R620 and the other is a ESXi guest on a Dell R720. Same 10gb NICs on each and both tied to the same switch physically.

Basically, what I was thinking was a combinations of curls for speed but like so:

curl http://$HOST/$TESTFILE -o /dev/null 2>&1

Would that eliminate disk as a consideration entirely? I don't care about that aspect -- I just want to see how fast stuff from a known trusted and calibrated system ($HOST) can get into the front door.