Home → Wiki → Troubleshooting → FIREFOX: How to Make Firefox Wait Longer for a Timeout
Launch Firefox and type the following into the browser's address bar:
about:config
Press "Enter" to view a Firefox warning page. This page points out that changes you make on the Settings page can be harmful if you do not know what you are doing.
Step 3
Click "I'll Be Careful, I Promise" to view the settings page. This page consists of a table containing preferences.
Type the following into the page's "Search" text box:
dom.max_script_run_time
When Firefox locates that preference, double-click the number that appears in the table's "Value" column and type a new value in the text box that appears.
The default value is 10. With that value, Firefox waits 10 seconds before displaying a timeout message.
Type a larger number to increase the delay time.
Click "OK."
Taken from: http://smallbusiness.chron.com/make-firefox-wait-longer-time-out-41249.html