Redmine

Hello, I'm just wondering why mongrel/webrick is so slow to perform certain tasks while others are extremely fast?!
I'm using mongrel-1.1.5, mysql-5.0.70-r1 and tried at first with webrick with the same result. When i'm editing something in the wiki section for example it's fast, but doing the same thing on issues is extremly slow, around 60s... :-(
I can't figure out what's going on... Below the production.log:

Processing IssuesController#edit (for 80.xx.xx.xx at 2009-05-18 11:33:19) [POST]
  Parameters: {"time_entry"=>{"comments"=>"", "activity_id"=>"", "hours"=>""}, "commit"=>"Submit", "action"=>"edit", "id"=>"27", "notes"=>"", "controller"=>"issues", "issue"=>{"start_date"=>"2009-05-06", "estimated_hours"=>"", "priority_id"=>"4", "lock_version"=>"2", "subject"=>"ERREUR NUMEROTATION OPE DE GAMME", "description"=>"Lorsque l on rajoute une opé la numerotation recommence a 2 au lieu de s ajoute a la précédente", "fixed_version_id"=>"", "category_id"=>"", "done_ratio"=>"0", "due_date"=>"", "assigned_to_id"=>"6", "status_id"=>"1"}, "attachments"=>{"1"=>{"description"=>"", "file"=>""}}}
Redirected to actionshowidAnomalie #27: ERREUR NUMEROTATION OPE DE GAMME
Completed in 60154ms (DB: 28) | 302 Found [http://xxx.xxx.fr/issues/27/edit]

As you can see this is not the DB the problem, but how to detect the problem ?!
Please help me!

If you need more information tell me!

Thanks.
Mike.