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perf(nav): drop the backdrop-blur behind the sticky header (scroll jank) #175

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Merged
marinom2 merged 1 commit into from
Jul 29, 2026
Merged

perf(nav): drop the backdrop-blur behind the sticky header (scroll jank) #175

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17 changes: 15 additions & 2 deletions components/nav.tsx
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,9 @@ function DesktopDropdown({
{open && item.children ? (
<div
role="menu"
className="absolute left-1/2 top-full z-50 mt-2 w-[420px] -translate-x-1/2 rounded-xl border border-bdr-soft bg-card/95 p-1.5 shadow-xl backdrop-blur-xl"
// bg-card/95 is already all but opaque, so backdrop-blur-xl bought
// almost nothing visually while still forcing a filtered layer.
className="absolute left-1/2 top-full z-50 mt-2 w-[420px] -translate-x-1/2 rounded-xl border border-bdr-soft bg-card/95 p-1.5 shadow-xl"
>
{item.children.map((c) => (
<Link
Expand Down Expand Up @@ -174,8 +176,19 @@ export function Nav() {
}, []);
const links = desktop ? ALL_LINKS.filter((l) => !l.webOnly) : ALL_LINKS;

// The header carries no backdrop-blur, deliberately. It is `sticky`, so the
// content behind it changes on every scroll frame - which means a
// backdrop-filter has to re-sample and re-blur the full width of the viewport
// 60 times a second. On a 4K display that is ~3840px of blur per frame, and
// WebKitGTK (what the desktop app renders with) is markedly slower at it than
// Chromium. It was the largest single cause of scroll jank in the desktop
// app, and invisible in profiles taken at rest: idle cost was zero.
//
// An opaque background lands within a hair of the same look on a dark theme
// for no per-frame cost. Blur is still fine on surfaces that do not sit over
// moving content - the dropdown above only exists while it is open.
return (
<header className="gradient-underline sticky top-0 z-40 border-b border-bdr-soft bg-background/65 backdrop-blur-xl supports-[backdrop-filter]:bg-background/55">
<header className="gradient-underline sticky top-0 z-40 border-b border-bdr-soft bg-background/95">
<div className="mx-auto flex h-16 max-w-6xl items-center justify-between px-5">
<Link href="/" className="group flex items-center gap-2" onClick={() => setOpen(false)}>
{/* eslint-disable-next-line @next/next/no-img-element */}
Expand Down
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