问题：
　　在Redmine部署使用后，发现更新事务时速度慢，进行了相关试验，去掉了可能影响速度的插件，仍然很慢。以下为对比试验：
　　1、包含12个自定义字段的项目，更新用时2136ms，记录如下：
Started PATCH "/issues/3115" for 127.0.0.1 at 2016-07-03 10:58:36 +0800
Processing by IssuesController#update as HTML
Parameters: {"utf8"=>"?"， "authenticity_token"=>"QNZR0IqhR6x6Otexs0D0w9b+2fWma/0YfiuOskbmGSQYMLB7lwQZJLB19GqANWSjh/6iubUif4l1X+E6nE8vhQ=="， "form_update_triggered_by"=>""， "issue"=>{"project_id"=>"5"， "tracker_id"=>"5"， "subject"=>"XX项目"， "description"=>"XX项目"， "status_id"=>"6"， "priority_id"=>"4"， "custom_field_values"=>{"57"=>""， "50"=>"XX"， "53"=>""， "11"=>""， "28"=>"XX"， "14"=>"2016-05-18"， "34"=>"2016-05-18"， "51"=>"2016-07-12"， "16"=>"0"， "3"=>"2016-05-18"， "23"=>""， "52"=>""}， "notes"=>""， "lock_version"=>"0"}， "was_default_status"=>"6"， "last_journal_id"=>""， "commit"=>"提交"， "next_issue_id"=>"3114"， "issue_position"=>"1"， "issue_count"=>"150"， "id"=>"3115"}
Current user: csl (id=26)
Rendered mailer/_issue.text.erb (15.6ms)
Rendered mailer/issue_edit.text.erb within layouts/mailer (31.2ms)
Rendered mailer/_issue.html.erb (0.0ms)
Rendered mailer/issue_edit.html.erb within layouts/mailer (0.0ms)
Redirected to http://127.0.0.1:8080/issues/3115?issue_count=150&issue_position=1&next_issue_id=3114
Completed 302 Found in 2136ms (ActiveRecord: 115.6ms)
　　2、包含51个自定义字段的项目，更新用时5745ms，记录如下：
Started PATCH "/issues/3890" for 127.0.0.1 at 2016-07-03 10:57:07 +0800
Processing by IssuesController#update as HTML
Parameters: {"utf8"=>"?"， "authenticity_token"=>"BdB8/SFFGD0lTT45NVQpA/dqUk/s/NExRrR0/orEDStdNp1WPOBGte8CHeIGIbljpmopA/+1U6BNwBt2UG07ig=="， "form_update_triggered_by"=>""， "issue"=>{"status_id"=>"2"， "priority_id"=>"2"， "assigned_to_id"=>""， "start_date"=>""， "due_date"=>""， "custom_field_values"=>{"57"=>""， "28"=>"XXX"， "16"=>""， "21"=>""， "22"=>""， "3"=>""， "23"=>""， "35"=>""， "37"=>"0"， "24"=>""， "25"=>""， "26"=>"0"， "38"=>""， "39"=>""， "40"=>""， "41"=>""， "42"=>""， "43"=>""， "59"=>""}， "notes"=>""， "lock_version"=>"3"}， "last_journal_id"=>"246"， "commit"=>"提交"， "prev_issue_id"=>"3904"， "next_issue_id"=>"3883"， "issue_position"=>"2"， "issue_count"=>"15"， "id"=>"3890"}
Current user: csl (id=26)
Rendered mailer/_issue.text.erb (31.2ms)
Rendered mailer/issue_edit.text.erb within layouts/mailer (93.6ms)
Rendered mailer/_issue.html.erb (15.6ms)
Rendered mailer/issue_edit.html.erb within layouts/mailer (15.6ms)
Rendered mailer/_issue.text.erb (15.6ms)
Rendered mailer/issue_edit.text.erb within layouts/mailer (31.2ms)
Rendered mailer/_issue.html.erb (0.0ms)
Rendered mailer/issue_edit.html.erb within layouts/mailer (15.6ms)
Redirected to http://127.0.0.1:8080/issues/3890?issue_count=15&issue_position=2&next_issue_id=3883&prev_issue_id=3904
Completed 302 Found in 5745ms (ActiveRecord: 66.8ms)
　　初步看来，解决办法是减少跟踪标签的自定义字段。
　　解决方案：
　　1、删除事务跟踪者，可以明显降低事务提交后的等待周期。因为事务更新需要发送邮件给跟踪者，而这个过程比较耗时。
　　2、减少自定义字段数。