Recently getting frequent "beachball of Death" on a "mid 2010" iMAC running High Sierra after updating to 10.13.6. [iMAC too old to use Mojave]. Happens both with Firefox… (read more)
Recently getting frequent "beachball of Death" on a "mid 2010" iMAC running High Sierra after updating to 10.13.6. [iMAC too old to use Mojave]. Happens both with Firefox 64.0 and its predecessor [I upgraded Firefox to see if this would cure the issue, but it did not]. "Refreshing Firefox", as suggested in Firefox Support may have helped in reducing the frequency.
The key aspect is that it is hard to invoke Forced Quit to get out of this freeze. "Beachball" prevents access to Apple logo to invoke it, and sometime prevents right clicking on Firefox icon in the Dock. Command/Option/ESC most always invokes the Force Quit dialog box, and may or may not show Firefox as "unresponding". After finally quiting Firefox, can start it up again and it will work for minutes or hours before this starts again.
Flash may be loaded, but is set to block its use.
Using Adblock Plus
No other extensions or add-ons
Vanilla apps -- standard Apple apps, plus Google Earth, Garmin which were not in use or background at the time and no problem when running these by themselves.
Trigger seems to be doing the update to 10.13.6 version of High Sierra -- Firefox problem in older iMacs ??
Thanks for your help. John
Have not had problems when in Apple apps