I have been experiencing Firefox taking up large amount of memory (in access of 100MB) after surfing for a while with many tabs open. So, I looked around on internet for a possible fix for the situation. After little searching, I found that you can disable the memory cache of Firefox by setting the value

browser.cache.memory.capacity=0 or
browser.cache.memory.enable=false

This did solve the problem, firefox was now using less memory than previously. But an interesteing thing started to happen. Some of the sites I surf regularly like my own digitalAmit, Sitepoint blogs and interestingly Google Desktop Search Homepage stopped displaying.

After tinkering with different attributes and values, I figured out that Firefox does not shows sites with Cache-Control: no-cache; when you disable memory cache.

Note: I am using Firefox 1.5 on Widnows. Other plateforms may not have this problem. Could someone please confirm this.

Update!: This has been already submitted to the bugzilla as bug 184304 with only one difference that instead of Cache-Control: no-cache; it is Cache-Control: no-store;