Share datasets via browser cache in the Dash app

[wkopp]

As suggested on the Dash web page: https://dash.plot.ly/sharing-data-between-callbacks
for large datasets, the computationally intensive pieces of code should be carried out outside of callbacks and sharing the data through the browser cache. This makes the interactive experience more fluent for large datasets.

Those performance considerations should be addressed at some point.

[wkopp]

Closing issue due to low priority