Your internet history, bookmarks, cookies, web form auto-fill information, and saved passwords will be kept. *'''Your ''internet history'' is a record of the websites you have visited.''' You can actually speed up Firefox by clearing your internet history and other history. How to clear the cache is explained [[How to clear the Firefox cache|here]], and how to clear history is explained [[Delete browsing, search and download history on Firefox|here]]. *'''Your ''bookmarks'' are the links you saved so you can visit them later.''' You can view your current bookmarks in the Bookmark Manager. Click the Bookmarks button, which is usually a little clipboard icon near your URL bar, and is grouped with a star icon, then click ''Show All Bookmarks''. *'''Your ''cookies'' are settings for websites.''' You do not need to worry much about cookies. *'''''Web form auto-fill information'' is history of what you typed in a text field.''' The menu usually appears in log-in forms when you're typing something similar to an entry stored in it, for your convenience. You do not need to worry much about web form auto-fill information. *'''''Saved Passwords'' are passwords for your online accounts that were saved when you logged into an account (e.g. Your Firefox Account), Firefox asked you if you would like to save it, and you chose to do so.''' Saved passwords automatically fill your username and password into a log-in form for your convenience. Your add-ons, search engines, download history, toolbar customizations, and settings will be restored to how they were when you first installed Firefox. ''You can re-install any add-ons, search engines, and toolbar customizations that you want after Firefox has reset. (although I wouldn't recommend that as an add-on may be causing the slowdown of Firefox)'' *'''''Add-ons'' are optional parts of your browser that can enhance your experience by adding more functionality and new features.''' An example of an add-on is ''Yahoo! Toolbar'', although that is technically malware (I just used it as an example because ''Yahoo! Toolbar'' is installed on your Firefox). *'''''Search Engines'' are settings of Firefox that determine which search website (E.G. ''Google''; ''Bing''; ''Yahoo! Search'') you will go to if you want to search for something and type your search query (E.G. "What is the best internet browser to download?") into the search bar or URL bar.''' *'''''Toolbar customizations'' are preferences that determine how Firefox's layout is like.''' For example, if you added ''Yahoo! Toolbar'' to the Firefox window by clicking the Menu button then clicking ''Customize'', this look will reset to the default look of Firefox after you have reset.

Appreciate the answer. Very informative. Thank you :)!