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.
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