Well, the entropy coding step is. Which is just one of multiple parts of the data compression. But entropy coding typically is the bottleneck in encoding/decoding speed, yes, and Duda's work is impressive (also because he took on Google when the latter didn't appear to keep their no-software-patents promise that they. made when they first started collaborating. The man stands up for his principles)
Also look at the time line! The dude started three 4-year masters courses (c.s., theo.math., theo.phys.) in a one-year stagger, so during 2001-2004 he was doing all three in parallel. The man seems to be quite the beast, even if he was probably able to reuse quite a bit of that math!