"Suspend Tab" for not loading inactive tabs is also important. I typically run about 50/50 in my active sessions in terms of active vs suspended tabs. "Search Tabs" and "Tab Mix Plus" are also very helpful. "Decentraleyes" also helps (mostly latency and privacy) by providing most not-bleeding-edge JS libs, fonts, etc locally only once.
Generally the first 1/3 of my tabs are long term tab groups I keep going back to for reference. These are almost all suspended most of the time they rarely change over the course of a single year. The second third is medium term tabs from projects I worked on but moved on from. I go through every month or two and bookmark projects I won't continue while closing the tabs. The last third is active tabs and changes day to day and week to week. I generally know the positions and relative groupings of all the tabs in the first 2/3 by heart. http://erewhon.superkuh.com/number-of-tabs-vs-date-2017.png http://erewhon.superkuh.com/whathappenedin2016accordingtotab...
Featurewise, UI-wise?