Native UI performance

These measurements cover steady frames rendered on the CPU with ui.Tester. They were taken on October 8, 2026 on Apple M5, macOS arm64, Go 1.27.1, with CGO_ENABLED=0 GOMAXPROCS=1. Each timing is the median of six sequential 300 ms samples after warming the view.

The Markdown rows, BenchmarkViewSteady and BenchmarkViewStream of ui/markdown, were taken on October 14, 2026, on a busier machine; see Markdown for the parser's own costs.

Element handles validate their owner, arena slot and build generation. Static label handles do not allocate. Input bindings, action queues and persistent identity bindings reuse storage once warmed. Composite controls can allocate callback closures; these fixtures do not cover every widget or interaction.

The label and list fixtures use the public API. The diff fixture uses the private renderer API and measures its steady-frame allocation floor.

What a frame costs

A window draws a frame only when something asks for one: input that may change what the view shows, Window.Update or Invalidate, a timer from After, or something that moves. Most frames build the view anew: your view function runs whole, and MyGo compares, lays out and places every element it built, changed or not, before it paints what shows. Layout reuses what did not change, but the work grows with how many elements the view builds, not with how much changed. These frames were measured on November 9, 2026, on Apple M5 with GOMAXPROCS=1 on a busy machine, with rows of a label and a button inside a Scroll:

List and Table build only the rows in view, so their frames cost what shows, whatever the length of the collection. Put long collections in them rather than in a Scroll that builds every row.

Hover. The pointer coming over an element, or leaving it, asks for a frame only when something looks at that element's hover. The toolkit's controls pick their hovered look as they paint, and a scroll container shows its scroll bars as it paints, so the frame only paints the last frame's elements again, without running your view. Calling Hovered as your view builds makes the pointer coming over that element, or leaving it, build the whole view anew. When only a drawing changes with the hover, read Hovered in its Draw callback instead:

card := ui.Box(c).Size(200, 120)
card.Draw(func(p *ui.Painter, r ui.Rect) {
	if card.Hovered() {
		p.Fill(r, c.Theme().SurfaceHover, 8)
	}
})

Passes. A control applies its input as its constructor returns, as Dear ImGui's do, so the code after it reads the new value. The view then builds once more in the same frame, so that what was built before the control shows the new value too: typing a letter builds the view twice. MYGO_FRAME_STATS logs how many passes each frame took (see Rendering).

Retained memory

A warmed view containing 1,000 labels retained approximately 2.50 MB of Go heap, measured over three samples. The measurement warms fonts and rendering, releases a warm view, forces collection, then measures a second retained view after ten frames and another collection.

This includes the headless rendering host. It does not measure native window process memory or GPU resources.

Measurement scope

Timing depends on the machine, rendering backend, content and activity in other processes. Small timing differences should be rechecked on several machines; allocation counts are more stable. These results describe steady frames and do not compare MyGo with another GUI framework.