Rated 2 out of 5 stars

I did some testing with the new Firefox 3.5 with and without Fasterfox lite 3.1.1.
It turns out that fasterfox hardly makes a difference on load times as shown by my test scenario.

For my test, I ran Windows Vista SP1, with a wireless DSL Modem @ 54Mbsp.
For measuring, I installed the Extend Statusbar addon to measure load times (I didn't use fasterfox's built in counter). Adblock plus is also enabled.

For the control group (this would be WITHOUT fasterfox lite) I have fasterfox disabled, but it's settings are reverted to Default so it should have no effect on load times.
For the experiemental group (with Fasterfox) I have the settings on TurboCharged.

Here are the results (in milisec); "Without" is without fasterfox, "With" is with it:
www.yahoo.com (opened on startup): Without:4.065 / With:4.047
www.en.wikipedia.org/wiki/main_page (logged in): Without:6.745 / With:7.619
www.youtube.com (logged in): Without:2.248 / With: 2.595
dan-ball.jp/en/javagame/dust (a java app): Without:2.230 / With:1.924

I've tested these sites multiple times and have gotten different results each time. Load times are variable, sometimes up to a millisecond different, and sometimes "With" won where "Without" didn't and visa-versa. For an addon that advertises it "will speed up your web browsing right out of the box", I would say this addon does not do its job, and don't recommend it.

This review is for a previous version of the add-on (3.1.1). 

Actual speed improvements may vary depending on the desired settings that are used and the presented testing situation. Since only internal browser settings are changed, it all depends on what settings work better for the user.