HI, please Copy/Paste about:preferences#privacy into the Address Bar then Enter. Go down to Heading Permissions and at the bottom that heading please make sure there is a Check Mark in the box for Prevent accessibility services from accessing your browser. Then please go up to General --> Performance and untick everything. change the recommended size lower then see how it runs. Note: 1 = No Multiprocessor = slow again. Try 2 Restart Firefox after making these changes please. Note : Hardware Acceleration is for Video Card, Monitor to see if remain off or to turn back on. Please install https://www.hitmanpro.com/ as 1x only use and check to see if you have anything that may cause this like bitcoin miners or other malware. Please let us know if this solved your issue or if need further assistance.