When I register a task linking a "Parent task", the system gets too slow.

The greater the amount of tasks inside the project, slower the tool become to record the tasks using the "Parent task" field. If the field "parent task" is not used the process is fast.

Eg: I'm working with a project that contains 965 task in hierarchy. When trying to create a task linking the field "Parent task", the recording time is 01min and 50sec.

Application data:

Environment:
Redmine version 3.2.2.stable
Ruby version 2.2.5-p319 (2016-04-26) [amd64-freebsd10]
Rails version 4.2.5.2
Environment production
Database adapter Mysql2
SCM:
Filesystem

Redmine plugins:
redmine_agile 1.3.10