It depends on what you do. Doing research requires a lot of resources (tabs) especially if you do it in an non-linear way. Consuming a content requires only on tab.
I open and use dozens of tabs (up to 100, then I bookmark all with one click and close all). But all tabs are active in memory in IE11 or Chrome so I can switch between them (sure I trade GBs of RAM for time, but that's okay). Firefox unloads tabs, so it reloads the page - that's better if you re-open Firefox as it only loads one tab instead of loading all tabs like in Chrome/IE but worse if you have it open and actually work in the browser. So for me it's a trade off, and I find it good I have a choice for different tasks I can choose the best way.
I open and use dozens of tabs (up to 100, then I bookmark all with one click and close all). But all tabs are active in memory in IE11 or Chrome so I can switch between them (sure I trade GBs of RAM for time, but that's okay). Firefox unloads tabs, so it reloads the page - that's better if you re-open Firefox as it only loads one tab instead of loading all tabs like in Chrome/IE but worse if you have it open and actually work in the browser. So for me it's a trade off, and I find it good I have a choice for different tasks I can choose the best way.