After Pharo 2.0 came out the community started with Pharo 3.0 which is still being worked on.
Independent from that many bug fixes for 3.0 were also backported to 2.0 and released
as Pharo 2.0 Summer release.
If you grabbed the initial Pharo 2.0 or the Pharo 2.0 Summer release you may have noticed that code loading is not as fast as it was in Pharo 1.4.
The main reason for this noticable slowdown was the introduction of the Ring package and proper packages (RPackage).
This has changed since yesterday with yet another update #20619. By using a cache the speedup on loading MC packages is now 3x or more.
So either update your image or just get a fresh copy of Pharo 2.0 from the file server. You will notice that loading Seaside or other packages from the Configuration browser is now much faster!