Heatmap rendering performance when many slider steps

Hi,

This one is somehow related to https://github.com/plotly/plotly.js/issues/6521 but slightly different.

• when working with 1000 slider steps (Plotly slider), the rendering of this heatmap is quite slow (between 1 and 2 frames per second when moving the slider): https://jsfiddle.net/wh1o2pyq/1/

• When working with 50 slider steps (Plotly slider), the rendering is super fast (more than 10 fps): https://jsfiddle.net/wh1o2pyq/2/

• When working with 1000 slider steps but with a HTML slider instead of the Plotly slider (<input type="range">), it is super fast: https://jsfiddle.net/5L9ykt76/

TL;DR: Plotly slider with many hundreds of steps seems to be a bottleneck for heatmap rendering

Does this mean the slider itself is re-rendered for each update, making the whole thing slow?

I believe that solving this issue could have massive improvement on the responsiveness of every Plotly/Dash dashboard using sliders :)

Any idea?

Comece pelas três reproduções vinculadas do JSFiddle, comparando o Plotly slider com 50 e 1000 etapas com o HTML range slider. Faça o profiling das atualizações do slider e da renderização da heatmap para identificar o gargalo; considera-se concluído quando o Plotly slider de 1000 etapas responde substancialmente mais rápido sem alterar o comportamento relatado da heatmap.