Please follow these steps to clear the cache of Firefox on your computer.
Note: The screenshots are from MS-Windows. The menus may vary on other platforms such as Mac OS/X or Linux.
1. Select the Options menu item in the Tools menu
2. Select the Privacy tab and click on clear your recent history
3. Select Everything in the drop down at the top and select what you want to delete then click Clear Now
This window is the one allowing you to clear your Firefox cache (or history).
Browsing & Download History — This cache is not important in regard to your display it is your history (Back button) and the list of websites you visited before.
Form & Search History — In most cases you can leave this content alone although the forms auto-fill can be a problem in some circumstances and thus deleting it may be useful.
Cookies — I suggest you do not delete your cookies; if you are logged in an account on some website, deleting all your cookies will log you out! Cookies very rarely participate in a rendering problem of your Snap! pages.
Active Logins — Like cookies, I suggest you don't delete those; active logins are similar to cookies used to keep connected with different websites.
Offline Website Data — I would delete offline website data because like the standard cache, it may get used if data is missing from the source website, which is not what we want.
Site Preferences — In most cases you do not want to delete this data. It includes your Firefox preferences when using different websites and it will not affect the rarely rendering of the site.
Once you are satisfied with your selection, click on the Clear Now button.