Tracking the most expensive operations when starting JabRef yields the following picture:

This shows that the following can be improved:

• First peak (500ms): do not load the group pane from fxml but create controls directly in the code. Done in Improve startup time #8035.
• Second peak (500ms): lazy initialization of the source pane in the entry editor (creating of the code area is expensive)
• Third peak (1300ms): This is comes only from passing the group name through the latex2unicode converter. Performance wise it's better to a) directly convert the group name to latex when the user adds/edits a group or b) cache the display name already in the Group and not only in the GroupViewModel which might be re-created a few times.

The other peaks correspond to things that need to be there (parse of bib file, init of webview in the preview panel,...).