When having a large number of emails, it is possible that the performance is affected after clicking the "Go to" button for opening an email, for example in the "Activity history" tab of an incident. Also, the Email tab can hang with the message "Preparing Form".
This article describes how to set up an index that improves the performance in this particular case.
Open the Journal business object and click on "Advanced" in the Details tab. Then click on "Add New Index" and select the "JournalType" field from the list and fill it as in the screenshot:
Add the index and save it.
After some minutes the index should be filled out and the performance should be improved.