Performance problems and production logs

Hi all!
I have this very slow action that loads a lot of data from an oracle
database and renders it in a nice html table. I am trying to
understand where all that time goes, but the production log is not
really helpful:

Completed in 13.85684 (0 reqs/sec) | Rendering: 0.67758 (4%) | DB:
1.43847 (10%) | 200 OK [http://railstation-a.siag.it/absences/absences/
filter_gantt]

so i get 0.67758 seconds to render the page, 1.43847 of db activity,
but a total of 13.85684 seconds to load the page. Where are the other
11,74079 seconds gone?
This is on apache Apache/2.0.54 with fastcgi.