Phoebus drastically slows down when alarm table contains a few thousand updating alarms.

[Peyton-Hill-CLS]

When the alarm table has a few thousand active alarms (in our case ~3000) the ui slows down to a point where its unusable. After some profiling and investigation it seems that individually updating each row of the table in

phoebus/app/alarm/ui/src/main/java/org/phoebus/applications/alarm/ui/table/AlarmTableUI.java

Line 687 in 14cf185

private void update(final ObservableList<AlarmInfoRow> items, final List<AlarmInfoRow> input)

causes the entire table to get resorted immediately after each row has been set. Ideally the table should be sorted after all the rows have been updated.

I've attached a screenshot of the visualvm profile that led me to this conclusion.