Firefox 1.5 users often complain about high memory utilization by the application. These memory leaks has undoubtedly been a big problem, although they have been cured relatively well in the latest editions of the browser. Despite this, many users report that the program utilizes a lot of memory and now the developers claim that this is a feature in the application, not a bug. This “feature” is simply a cache for websites, which keeps the last browsed sites in the memory for faster browsing back and forth to recently visited sites. The amount of saved pages depends on the amount of RAM installed in the computer, but it should never be more than eight pages at the same time. However, this seems to be the explanation to the webbrowsers high memory utilization in many cases.
Source: Inside Firefox
