Execution of Notebooks are very slow compared to Classic Jupyter

[DonJayamanne]

Run 200 cells in classic Jupyter = 0.5s
Run 200 cells in custom Editor = 9s
Run 200 cells in Native Editor = 35s

Last year I recall making some changes to ensure the perf was faster

Suggestions:

• Synchronize messages only when we have widgets (I did this last year, either the code has been accidentally removed or still there & not workign, or other)
• Don't wait for VS Code to update the output