We have been encountering a lot of CPU timeouts when editing a journal entry that has a lot of journal items in it (over 50).
When a journal entry is edited and then saved, the validation is processed for every journal item (even ones that have not been modified). This can be seen by creating a journal entry that has a lot, say 100, journal items. Then editing the journal entry and adding an additional journal item.
Performance can be improved a lot by only performing full validation on any journal items that have been added or edited, and not re-processing the existing unchanged journal items. Alternatively, ensuring that the journal item validation is triggered as each journal item is entered/edited and saved (instead of waiting for the whole journal entry to be saved).
This issue is mainly a problem with the web client. If you test functionality on the GTK client then you find that a large journal entry can be edited and saved fairly quickly. However, when doing the same change in the web client this can cause a long processing time and CPU timeouts.