Poor optimization and doesn't even remove the top bar so it's making things worse.

This extension has been one of my all-time favourite. Shout out to the author for making Firefox a better production utility.

valo

The best way I've found to manage Tabs in FF. Coupled with a little userChrome.css magic to hide the old tab bar, and the experience is magical. TY Piro, for making this extension. :-D

Удобное расширение, спасибо!

Very cool but a bit overrated. Options are messy and some don't even work (special actions on 'new tab').

Отличный аддон

Было бы отлично если бы он умел опционально скрывать дефолтную панель вкладок сверху.

Nice!

基本满足侧边栏要求。但是有问题：
用firefox color 自定义颜色时，“树状标签页“这里无法自定义，这就很尴尬，侧边栏和工具栏中间永远隔了一块。
对比edge。edge的侧边栏目前来说应该是最简洁易用的了，外观功能简洁，固定标签一目了然，搜索标签右键一步到，隐藏边栏edge还显示图标，不得不说edge在设计功能易用上花了心思的。
希望作者参考一下edge垂直标签栏做一些优化，谢谢。

Literally the reason I use Firefox over Chromium browsers.