Detect end of rendering

[Jopenergy]

Hi, First things first: this pivot-table is just amazing! Thank you for all the work done yet!

I just would like to know if there is a way to detect the end of data rendering (around 60 000 lines of data). I would like to display a loader during the downloading time AND the rendering time because for the moment I get the pivot-table empty for 10 seconds before the data are displayed, it's not totally users friendly, they get the feeling it's not working...

Thank you in advance for any help