1- In the Address bar, type about:config and press Enter
2- Click on I'll be careful, I promise!
3- In the about:config page, search for the preference dom.max_script_run_time
4- Double click on dom.max_script_run_time and type value 20
Note: The default value is 10
5- Press OK
With scripts now allowed to run for longer times, you may no longer receive the prompt.
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