Is it possible to disable "hovered" state updates until resizing begins?

[evanfrawley]

Hello,

First off, thank you for the major version bump this past December with the additional support for other css units 😄

As I've been using this project, I am noticing that both the <Separator> and resize hit regions are rather eager to fire updates when they're hovered, causing rerenders of the panels, even when resizing is not occurring.

He is a video -- for reference, I am only clicking + resizing in the section with the <Separator> handle variant. Moving vertically on that handle (before clicking) also fires rerenders of the panels as well.

CleanShot.2026-01-28.at.15.12.26.mp4

I am wondering if it is possible to disable or reduce these eager updates? I am also happy to take a stab at updating this if you can point me in the right direction.

Thanks!

[bvaughn]

Re-rendering the Panel component is very fast. Trying to prevent all re-renders is probably over-kill in this case (unless you're observing an actual performance problem it's causing).

FWIW this issue doesn't occur any more in the refactor branch I've been chipping away at (#598) but I also don't think it's causing any problems in the current release either.

[bvaughn]

Give this a build a try instead when you get back:
react-resizable-panels-4.5.4-alpha.0.tgz

Seems I can cut out the unnecessary renders with a pretty small patch (#638) so I'm willing to publish it before #598 ships, if it helps your case.

[evan-sift]

Wow, that has significant improvements! Mouse events on the handle are only triggering rerenders on the handle itself (as I'd expect) and the panels are not updating extraneously. Really mind blowing to you see that get fixed that so quickly, thank you!!

[evan-sift]

Providing further context of what was rendering:

┌──────┌────────────────────┐
│      │                    │
│      │                    │
│ list │      chart         │
│      │                    │
│      │                    │
│      │                    │
│      ┌────────────────────┐
│      │      legend        │
│      │                    │
└──────└────────────────────┘

there is separator to the right of the list, and between the chart and legend

each mouse hover would cause several rerenders to each panel. My guess was that the biggest offender wsa probably the chart, which cares about its own size and on each render figures out how it needs to draw the data. And the area for Chart/Legend could have multiple chart/legend panels, sort of like VSCode's tab layout.

anyway, the reduction of panel updates is a significant performance boost 😄

[bvaughn]

Thank you for confirming the fix! (and thanks for the coffees! 😄 )

[evan-sift]

just installed and confirm it works from 4.5.4!

[bvaughn]

Just published react-resizable-panels@4.5.4

[bvaughn]

Awesome 😎 Thanks

…

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