[DropDownMenu] Preliminary step toward virtualization

[oliviertassinari]

This is a preliminary step toward adding support for react-virtualized and react-list.
We need to stop cloning children and doing heavy computation with them. cc @bvaughn.

Hopefully, that's already improving the performance of the rendering method (#2787).
Before : 446 ms to open the Long example

After : 374 ms to open the Long example

[bvaughn]

Looks like a nice improvement. :)

I found myself wondering how much more time you could save if you got rid of the other child-cloning that's happening inside of the Menu component. For me it takes your "Long example" time from ~350ms down to ~190ms. That's a pretty nice savings, although it would require some non-trivial changes to Menu and that might rule it out as a possibility. Otherwise it might be worth considering moving towards supporting a child-factory-function instead of pre-declared MenuItem children.

[oliviertassinari]

@callemall/material-ui This is a friendly ping :).

[alitaheri]

Sorry for the late response 😅

I think itemIndex is more readable.

[alitaheri]

All good aside from that 😅

[oliviertassinari]

@bvaughn Wow, that's a pretty nice time saving. Cloning element, as we can expected, is pretty expensive.

Otherwise it might be worth considering moving towards supporting a child-factory-function instead of pre-declared MenuItem children.

The API of this component used to be something close to a child-factory-function.
I'm gonna keep investigating the integration, I will ping you If I need help :).

[bvaughn]

Congrats on getting the first step merged! I'm looking forward to seeing what's next. :)