- Type about:config in the address bar and you will get the hidden configuration page – similar to the windows registry editor.
- In the filter box, type dom.max_script_run_time. This will filter the options and will display only the dom.max_script_run_time.
- Right-click it and choose Modify. A box pops up. Change the number to something bigger like 20. This is the maximum time a script can run before Firefox considers it