I suspect this is slowing down my start-up time but I have no way to check how

Broken on Android! Beware! Only saves a few tabs (if lucky), I had 43 tabs, it only saved one. I tested again with twelve, and it only saved three. I was also unable to recover the lost tabs through 'recently closed' in history. Wonderful on PC, disastrous in Android.

Usability wise and task wise: it is to the point and does exactly what you want it to do.
Accessibility wise tho? Not so much. The only thing that would make me bump it up to a 4 or even 5 star review would be if the tabs could be synced to other devices or to your Firefox account you use to sync tabs and the such. There have been many cases where I had to clear cache because something was acting up or my cache was just bogging up space and lost my tabs as a result of said clear.

This is a great idea implemented really well!

AN EXCELLENT & NECESSARY ASSISTANCE TO HAVE. I CANNOT DO WITHOUT SINCE MY WORK IS PROVIDED BY THE WORLD INTERNET SYSTEM TO DATE. THANK-YOU. ALL BROWSERS NEED THIS AVAILABLE.

VANESSA PEREZ OF DIVINE CREATIONS *922

I love this extension, it's everthing I wanted to organize links I use for work, entertainment, study but miss a dark mode.

No tengo.

Added OneTab, and it immediately closed all my tabs.
No tabs to restore.
No chance to get tabs back.
DO NOT INSTALL THIS ADD !!!