One option is the Duplicate Tab Closer, which prevents browser windows that are opened up by accidentally being called up by a second or third time, thus consuming unnecessary extra memory.
changing the setting from “do nothing” to “close tab automatically.”
The second add-on, called Max Tabs, prevents open browser tabs from running riot by enabling users to define a maximum number of open tabs. If the limit has been reached, the add-on prohibits every attempt to open up an additional tab. – dpa