Highlights Tab Previews! Congratulations to DJ for getting these landed. Currently disabled by default, but you can test them by setting `browser.tabs.cardPreview.enabled` to true ...
There's a dropdown next to the tab strip that shows all the tabs (and their titles/names) in a dropdown scrolling list.
Alternatively, the omnibar can search tabs, for the specific one you're looking for. Ctrl+Pageup/Pagedown (and Ctrl+tab) can also fine scrub through the tab strip.
You can also fix it with a custom userChrome.css, which lets you set the min and max tab width before they begin to scroll.
In other words you can make it so that if one or two tabs are open they take all the space and the more you open they all shrink equally up to a point.
To mitigate this you can go to about:config (write it in the address bar) and search for a setting called browser.tabs.tabMinWidth, I usually change the number to 20 (the default minimum width is like 70) and tabs are allowed to become roughly as narrow as in chrome. It's a much simpler and stabler option compared to custom CSS