Via Firefox Options
Click the "Tools" menu, and then select "Options." If you're using OS X, launch the settings utility by clicking the "Application" menu, and then selecting "Preferences." On Linux, click "Edit," and then select "Preferences."
Click the "Advanced" button, and then select the "Network" tab.
Check the box labeled "Override automatic cache management.”
Click the down arrow on the "Limit cache to" spin box to highlight the current cache size, and then type "0" (without the quotes). The cache still contains your old data at this point, so click the "Clear Now" button to clear the cache completely.
Click "OK" to save your new cache setting.
Type "about:config" (without the quotes) in the browser's address bar, and then press "Enter" to load your Firefox configuration settings. If Firefox displays the warning "This might void your warranty!", click the "I'll be careful, I promise!" button.
Type "browser.cache.disk.capacity" (without the quotes) in the search box to filter all settings except the one for cache size. This eliminates the possibility of changing the wrong setting by mistake.
Double-click the search result, type "0" (without the quotes) in the pop-up input box, and then click "OK."
Close the about:config tab when you are done.
- Information in this article applied Firefox 27.0. It may vary slightly or significantly with other versions of Firefox.
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