Thanks for the update!
Looking at the text preceding the link, I notice you propose to share a NotesSession object. But Andrew shows that this does not speed up anything, it slows stuff down.
Idea: Is it possible that the first call to OpenLog creates a Session specifically for use by OpenLog, which survives until Notes is exited or a timer goes off. (Like 5 or 10 minutes.)
This way Session object creation overhead goes way down, without the user of the OpenLog class having to manage Session objects.