I started doing some "Cocoon Profiler" on site-author.
Processing index.html four times then looking at cprofile.html

Compared Dispatcher-enabled site-author with the profile
of skins-based site-author running on another port.

Still not sure how to interpret results, but
here are some initial observations.

Using the default theme ...

Some pipelines seem to be requested twice or more
for each page view, e.g.
resolve.contract.html.siteinfo-feedback

Using the pelt theme ...

Seems to process an extra resource called license.html
and its associated pieces.

Total of about 100 pipelines were processed compared
with about 45 pipelines for the skins-based site
and about 40 pipelines for the default dispatcher site.

-David