Slow down of autosave due to tasklist update
Tasklist dialog is updated when a page is indexed on autosave, for large number of tasks in the database (not in the page being saved) this blocks the autosave and causes lag. In addition to that the tasklist dialog is not properly disconnected when it is closed, so opening it several times results in multiple instances, amplifying the issue.
Two fixes needed:
1/ Detach dialog update from indexing - make it asynchronously / update on focus of the dialog / ..
2/ Fix destruction of tasklist dialog
In addition updating of the dialog may be improved.
See discussion in related question for details