Take it with a grain of salt. There are so many ways to measure speed that you can concoct ways to make almost any phone seem faster than another. In terms of pure specs;
-SGS2, Nexus, and iPhone 4s all have the same exact CPU, with the SGS2/Nexus at 1.2ghz and the iPhone at 800mhz. So, the iPhone has the slowest CPU.
-The iPhone 4s has the fastest GPU, not even close. The Nexus and SGS2 have different GPUs with different strenghts/weaknesses. They are about equal, with different apps/games/tests favoring one or the other.
-Nexus/SGS2 have 1GB of RAM while the iPhone 4s has 512MB. However, the iPhone 4s doesn't multi-task to the same degree, so the amount of RAM there is adequate.
And then, there's the user-measurable speed. How smooth is the interface? The iPhone is renowned for this aspect, the SGS2 has made large strides over previous Android handsets, and the Nexus looks to redefine the stock UI. So, we'll have to see after the Nexus releases.
Also, the article is flat out wrong. It cites the same BS "SGS540 is from 2007" line that was thrown around here. The SGX540 went into development in 2008, hit actual silicone in 2009, and did not release in a shipping product until 2010. This article is like saying that "although the Xbox 360 came out in 2005, it went into development in 2001, so we'll just say that it's 10 year old tech." Also, the version of the SGX540 in the Nexus is so insanely overclocked compared to the first-generation version that their performance is nowhere near identical.
Rest assured that the article you linked is an outright fabrication with no basis in fact.