Mozilla has been well aware of this problem for years. See this blog post from 2008, 3 years ago, detailing the changes that went into optimizing memory use for

Mozilla has been well aware of this problem for years. See this blog post from 2008, 3 years ago, detailing the changes that went into optimizing memory use for Firefox 3, including switching to jemalloc to decrease fragmentation: http://blog.pavlov.net/2008/03/11/firefox-3-memory-usage/ http://blog.pavlov.net/2008/03/11/firefox-3-memory-usage/