After thinking it through...
...and asking a bit of advice, I decided to share this.
First the two replies to the message on the OpenBSD mailing list:
https://www.mail-archive.com/source-changes@openbsd.org/msg99159.html
https://www.mail-archive.com/source-changes@openbsd.org/msg99161.html
This tells us who discovered it (Ben Gras of VUSec) and what they named it (TLBleed).
A Google search for VUSec and four mouse clicks leads to this:
https://www.blackhat.com/us-18/briefings/schedule/#tlbleed-when-protecting-your-cpu-caches-is-not-enough-10149
After reading a bit I disabled hyperthreading from the BIOS on my systems. I think that until I know more the folks at OpenBSD are right and it's better to play it safe. I am writing this because I think that security by obscurity is no security at all.
Biting the hand that feeds IT
