Here is what fixed the problem for me with firefox.
This issue is caused by a timeout setting in firefox.
To fix it, you’ll need to access the hidden configuration page in Firefox. Just type about:config in the address bar and click enter.
Scroll down to the dom.max_script_run_time option, 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 ‘unresponsive’.