I do run a couple of VMs..150 tabs? You're definitely the target audience for Vivaldi - as far as their tab management goes - but since it's based on the same Chromium engine memory usage won't really differ. Do you use an extension like The Great Suspender to reclaim memory from idle tabs? If not it might be worth considering, 64gb is a lot of RAM. That's server territory.
The tab count is mostly due to the fact that I’m doing a lot of testing on here often times and I’m switching between multiple admin panels etc. I stopped using the great suspener because apparently it has been taken over by a new developer who has injected malware