The test: The effect of Firefox addons on bandwidth consumption
Date: November 27, 2011 (Updated with additional figures December 4, 2011)
Dataset: the Alexa top hosts list, with country code specific dupes (ie google.in following google.com) removed. The top 150 sites were then opened in order and I scrolled to the bottom of each page with the mouse cursor in the middle, engaging mouseover code as in normal browsing.
Methodology: All browser setups were self-contained. I created a .mozilla-vanilla, .mozilla-noscript, and so on, independently, and began each test with e.g. rm -rf .mozilla; cp -Rp .mozilla-noscript .mozilla before starting Firefox. Only one copy of FF was ever run at a time. The DNS cache listening on 127.0.0.1 was also cleared before each test, and the packet filter statistics were "refreshed" with a simple pfctl -f /etc/pf.conf. All traffic-generating software (dhclient, ntpd, etc.) was killed before beginning the experiment. Packet and bandwidth statistics were pulled from pfctl -vs rules.
Operating System: OpenBSD 5.0
Firefox: 5.0 with the default settings
NoScript: 2.2 with the default whitelist
Adblock Plus: 1.3.10 with the default Easylist, updated November 27, 2011
MVPS: updated November 23, 2011. (Not technically a FF addon.)
Pre-experiment assumption: Adblock Plus would deliver the greatest independent savings. (I was wrong.)
|NoScript + MVPS||94648||7888||59776989||923403||60700392||45.8798%|
|NoScript + Adblock Plus||97281||8595||60884205||1022991||61907196||44.8038%|
|Plain Firefox 5||181433||12877||110661642||1496984||112158626||0.0%|
In short, NoScript plus ad blocking in some form may reduce bandwidth usage in half. Additionally, NoScript is more effective than Adblock Plus in reducing bandwidth.
December 4, 2011 Update
I wanted to revisit this test, first to try reproducing results from the first test, and second, to determine how mass-whitelisting would affect bandwidth usage. For this test, I imported the top 150 sites into NoScript's whitelist while keeping the original whitelisted entries. Thus, every site I tested had been pre-whitelisted in NoScript. This test group is the "Extended Whitelist." I then proceeded with the test as normal, and here are the results:
|NoScript + Default Whitelist||102467||9684||63808382||1132686||64941068||41.8144%|
|NoScript + Extended Whitelist||133711||11022||83395319||1286679||84681998||24.1270%|
|Plain Firefox 5||182761||13701||110034209||1576125||111610334||0.0%|
NoScript 2.2.1 was used in the Dec. 4 test.
The bandwidth savings of NoScript from test #2 closely mirror those in test #1.