[ccffph]

I use an MBP 15" 2017 with 16g ram, 300+ tabs open as I type, with tree style tabs on firefox. No issues. I would complain about ram usage, but there is certainly no high cpu usage from vertical tabs.

[lordnacho]

Are any of your tabs gmail? I think that's the main culprit, but I'm not sure it's the only one. Slack as well.