Removed unnecessary calls to _recompute_all_models() to speed up adding roots (#11739)
Removed unnecessary calls to _recompute_all_models() to speed up adding roots (#11739)

* Removed unnecessary calls to _recompute_all_models() to speed up adding roots

* Corrected last commit so that general calls to add_root() still call recompute_all_models(), and that is only worked around in special situations.

* Wrapping calls to add_root() within push_all_models_freeze()

* Made last commit more elegant by getting rid of loop

Co-authored-by: Efrem Braun <22fb8c2f82cdfa3ceae7ecd18a943e654020297b@gmail.comm>
bokeh/bokeh,bokeh/bokeh,bokeh/bokeh,bokeh/bokeh,bokeh/bokeh