Very slow index.html.erb

[Kiolul]

Hello,

I have 2 redmine servers installed.
One with the Backlog plugin and another without.
The server with the plugin is very slow on project's pages, near 20 sec to display the list of them...
The other doesn't encounter this speed isssue.

My configuration:
Environment:
Redmine version 2.3.2.stable
Ruby version 1.9.3-p0 (2011-10-30) [x86_64-linux]
Rails version 3.2.13
Environment production
Database adapter Mysql2
Redmine plugins:
clipboard_image_paste 1.7
external_link 0.0.1
redmine_backlogs v1.0.6
redmine_improved_searchbox 0.0.3
redmine_ldap_sync 2.0.2.devel
redmine_workload 1.0.1
sidebar_hide 0.0.4

My production.log:

Started GET "/projects" for 192.168.10.157 at 2014-01-27 15:57:24 +0000
Processing by ProjectsController#index as HTML
Current user: quiblier (id=3)
Rendered projects/index.html.erb within layouts/base (15036.4ms)
Rendered plugins/redmine_improved_searchbox/app/views/redmine_improved_searchbox/_redmine_improved_searchbox_partial.html.erb (1.8ms)
Rendered plugins/clipboard_image_paste/app/views/clipboard_image_paste/_headers.html.erb (1.9ms)
Rendered plugins/redmine_backlogs/app/views/hooks/_rb_include_scripts.html.erb (5.5ms)
Rendered plugins/sidebar_hide/app/views/sidebar/_hideButton_partial.html.erb (1.1ms)
Rendered plugins/clipboard_image_paste/app/views/clipboard_image_paste/_add_form.html.erb (3.5ms)
Completed 200 OK in 15209ms (Views: 15193.3ms | ActiveRecord: 5.9ms)
Started GET "/rb/server_variables.js" for 192.168.10.157 at 2014-01-27 15:57:40 +0000
Processing by RbServerVariablesController#index as JS
Current user: quiblier (id=3)
DEPRECATION WARNING: Passing a template handler in the template name is deprecated. You can simply remove the handler name or pass render :handlers => [:erb] instead. (called from realtime at /usr/lib/ruby/1.9.1/benchmark.rb:295)
Rendered plugins/redmine_backlogs/app/views/rb_server_variables/show.js.erb (5.2ms)
Completed 200 OK in 10ms (Views: 6.2ms | ActiveRecord: 0.3ms)

Thx for your help.
Regards.