Rake asset: precompile takes 28 minutes on 1.9.2

I have a pretty large rails application (Rails 3.2.3) using an asset pipeline. There are quite a few files in the resource folder.

In section 1.8.7, startup rake assets:precompiletakes 4 minutes. This is a long time, but because of the huge amount of assets I am ready to endure it.

The problem is that after updating the application to 1.9.2, the launch rake assets:precompiletakes 28 minutes .

Here are the relevant versions of gem:

rails (= 3.2.3)
uglifier (1.2.3)
  execjs (~> 1.3.0)
therubyracer (~> 0.9.9)
  libv8 (~> 3.3.10)
sprockets (2.1.2)
  hike (~> 1.2)
  rack (~> 1.0)
  tilt (~> 1.1, != 1.3.0)

When I tail -f log/production.log, I see that the compiled assets and I can’t determine the long delay for one asset (although it seems like I see the same assets several times in the logs - presumably because there are several steps for each asset?)

, ?