Downloads become dependent on cursor movement to complete the download.
After downloading a large number of files the download window will show the files being downloaded but seems to stall. However, when I move the cursor with the mouse anywhere on the screen the download will progress with the download as long as the cursor is being moved if the cursor is stopped moving the download stops.
Alla svar (1)
Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).
- Don't make any changes on the Safe mode start window.
- https://support.mozilla.com/kb/Safe+Mode