30% this time is less than 30% the last time they showed a speed increase.
Start off with 100%, 30% faster gives you 70% of the original time. Take off another 30% and now you're doing it at 49% of the original time. Now remember, we're on the 5th iteration of XX% faster, since the original chrome was XX% faster than (whatever they were compare it to).
Its not likely most people will notice a 30% increase on most pages, especially Googles own pages.
When you're talking about taking 30% off of something that already loaded in 1 or 2 seconds, no one notices, you get more delay from your overloaded cable modem than from the browser.