It happens to me sometimes. When I open too many tabs, some of them can be really hard to locate. A solution to this is to move the active tabs to the end or beginning of the tab bar, but doing so when there are so many tabs can be difficult sometimes. Fortunately, tabsmack makes the pain goes away.
Once installed, the extension adds two buttons on the main toolbar.
All you need to do to move any tab is to select the tab and then click the appropriate button. Hit the left button to move the tab to the beginning and the right tab to move it to the end.
Tabsmack, created by magopian, supports hotkeys as well. Accel-alt-home to send tab to the start, and accel-alt-end to send tab to the end of tab bar, with accel being either “ctrl” on windows and linux or “command” on mac.
Another way to easily locate a tab is to add a color. To implement this solution, you can use add-on such as Highlight Tab.
Right-click on the tab, select Highlight Tab and click on the color that you want to mark the tab.