Improved Analyses loading
I finally succeeded in speeding up loading analyses from the database. In reality retrieval from the database
is quite rapid (depending on network connection) but converting to DVCIsotopeRecordViews was time consuming. One
earlier optimization was to limit the number of progress.change_message calls. change_message eventually
calls Qt.QApplication.process_events which takes ~80ms each call. So loading of analyses was already penalized
80ms because of the progress bar. I will continue to investigate the progress window but a more significant speed up
was achieved by eliminating the concept of an IsotopeRecordView. (eventually this model should be extended to the
other record view classes).
So… the major change was to keep the session open when a SessionCTX is exited and to temporarily disable
expire_on_commit when retrieving analyses. Since the analyses do not change in the database it is safe to
disable expire_on_commit
