Install Mozilla Firefox Open your Internet browser and go to the Mozilla Firefox download page. Click the Free Download button in the center of the page. Once the download has completed, click Run or on the download itself (usually in the lower-left corner of your browser window). Follow the prompts to install Mozilla Firefox.Why is Firefox not working on Windows 10?
If Firefox is slow on your Windows 10 PC, the problem might be your antivirus. Antivirus tool is a necessity, but sometimes your antivirus can interfere with your web browser and cause slowdowns. Many antivirus tools also tend to install various extensions in order to offer extra protection, but these extensions can also slow down your browser.