By Will Fowler.
Allows you to easily find tabs with keyboard shortcuts and searching.
Because you have too many tabs open, and you remember very little about the tab you need to switch to.
See the addon in the store, that should do the trick.
Ctrl + Shift + F (Command + Shift + E on Mac) will open the tab switcher, type in the tab you vaguely recall, hit enter and go. Use up/down arrows to select from the list.