With time, a browser’s memory usage can go up significantly. Firefox suffered with these memory leaks for a very long time. The Mozilla team have been fixing these issues in the past few months. They worked really hard on it and with each release, Firefox became more faster. The new version they released today carries a a patch for a big issues which caused the browser to eat your memory.
The problem is with add-ons. Poorly written add-ons… According to the research, even the most popular and widely used plugins can cause these issues. Sometimes, a plugin can keep a copy of the webpage in the memory for its use. After you close that tab, Firefox will remove the page from the memory. But some add-ons won’t. The new Firefox 15 fix this issue by cleaning the memory used by add-ons as well. For a full list of changes, please check the release notes.
To update Firefox, go to Firefox > Help > About Firefox. If you don’t have Firefox, download the latest version from here : http://www.mozilla.org/en-US/firefox/new/. After this update, all the upcoming updates will be downloaded and installed on your system automatically. No need to manually update!