Reduce the server load by asking firefox to not cache on disk

[Petter Reinholdtsen <pere@hungry.com>]

My friend Alf Tonny Bätz in Narvik told me that he changed the Firefox
setup to disable disk caching, to reduce the network traffic on the
diskless workstations and reduce the load on the server.

This is the change he did in
/usr/lib/firefox/default/preferences/firefox.js:

// Prevent disk loading, cace to mem
pref("browser.cache.disk.enable", false);
pref("browser.cache.offline.enable", false);
pref("browser.cache.memory.enable", true);
pref("browser.cache.memory.max_entry_size", -1);

He report that the result was that the load average went down 3 when
60 pupils logged in and started firefox at the same time.  The load
used to be around 5 for quite a while during login, and now it is
around 2, and it is quickly falling even lower.

This seem like something we should put in our
debian-edu-config/share/iceweasel/defaults/preferences/debian-edu.js
to enable by default.  Any objections?

-- 
Happy hacking
Petter Reinholdtsen