At times, my Firefox seems fail to load websites. The loading ciricle "icon" just keep at the tab title for a long time, and nothing can be displayed. When this problem happens, all tabs will get the same issues, and I have noticed the Firefox process has a high CPU consumption at that time as seen in Windows Task Manager. I tried to close the Firefox with the "x" button at top-left corner of the windows, but after then when I start a new FIrefox it will says there is a firefox running. I have to eventually use Windows Task Manager to kill the process, then restart Firefox to resume.