optimize html and svg renderPerNode/renderPerEdge to only update the single node/edge

[sgratzl]

It would be great if

optimize html and svg renderPerNode/renderPerEdge to only update the single node/edge

[pshurygin]

@sgratzl Hey! I was not sure if I should create an issue for that or not, but I have a suggestion for an easy performance optimisation for the extension.

I've stumbled upon a very poor panning and zooming performance when using html layer + renderPerEdge + ~40 custom html nodes. My nodes were only created once using init option and never really re-render much, but each node was a pretty sizeable html subtree.

I could improve the performance drastically by manually adding will-change: transform to the html layer wrapper div. While this can be easily done manually, I thought that maybe you would want to do this by default within the extension code itself.

[sgratzl]

according to https://developer.mozilla.org/en-US/docs/Web/CSS/will-change

Warning: will-change is intended to be used as a last resort, in order to try to deal with existing performance problems. It should not be used to anticipate performance problems.

given this warning I'm hesistant to add it by default. However, as you noted it can be easily added manually using the init option in renderPerNode