diff --git a/app/internal/window/os_android.go b/app/internal/window/os_android.go
index be90954a..15d3bc32 100644
--- a/app/internal/window/os_android.go
+++ b/app/internal/window/os_android.go
@@ -384,6 +384,7 @@ func (w *window) draw(sync bool) {
 	ppdp := float32(w.dpi) * inchPrDp
 	w.callbacks.Event(FrameEvent{
 		FrameEvent: system.FrameEvent{
+			Now: time.Now(),
 			Size: image.Point{
 				X: int(width),
 				Y: int(height),
@@ -392,7 +393,6 @@ func (w *window) draw(sync bool) {
 			Config: &config{
 				pxPerDp: ppdp,
 				pxPerSp: w.fontScale * ppdp,
-				now:     time.Now(),
 			},
 		},
 		Sync: sync,
diff --git a/app/internal/window/os_ios.go b/app/internal/window/os_ios.go
index fa710fa6..f63c24c4 100644
--- a/app/internal/window/os_ios.go
+++ b/app/internal/window/os_ios.go
@@ -108,6 +108,7 @@ func (w *window) draw(sync bool) {
 	const inchPrDp = 1.0 / 163
 	w.w.Event(FrameEvent{
 		FrameEvent: system.FrameEvent{
+			Now: time.Now(),
 			Size: image.Point{
 				X: int(params.width + .5),
 				Y: int(params.height + .5),
@@ -121,7 +122,6 @@ func (w *window) draw(sync bool) {
 			Config: &config{
 				pxPerDp: float32(params.dpi) * inchPrDp,
 				pxPerSp: float32(params.sdpi) * inchPrDp,
-				now:     time.Now(),
 			},
 		},
 		Sync: sync,
diff --git a/app/internal/window/os_js.go b/app/internal/window/os_js.go
index a5bc5956..551a645f 100644
--- a/app/internal/window/os_js.go
+++ b/app/internal/window/os_js.go
@@ -413,9 +413,9 @@ func (w *window) draw(sync bool) {
 	w.mu.Lock()
 	w.scale = float32(scale)
 	w.mu.Unlock()
-	cfg.now = time.Now()
 	w.w.Event(FrameEvent{
 		FrameEvent: system.FrameEvent{
+			Now: time.Now(),
 			Size: image.Point{
 				X: width,
 				Y: height,
diff --git a/app/internal/window/os_macos.go b/app/internal/window/os_macos.go
index 224bb972..fef2acda 100644
--- a/app/internal/window/os_macos.go
+++ b/app/internal/window/os_macos.go
@@ -228,10 +228,10 @@ func (w *window) draw() {
 	width := int(wf*w.scale + .5)
 	height := int(hf*w.scale + .5)
 	cfg := configFor(w.scale)
-	cfg.now = time.Now()
 	w.setStage(system.StageRunning)
 	w.w.Event(FrameEvent{
 		FrameEvent: system.FrameEvent{
+			Now: time.Now(),
 			Size: image.Point{
 				X: width,
 				Y: height,
diff --git a/app/internal/window/os_wayland.go b/app/internal/window/os_wayland.go
index 2a683666..87209bb6 100644
--- a/app/internal/window/os_wayland.go
+++ b/app/internal/window/os_wayland.go
@@ -1385,9 +1385,9 @@ func (w *window) draw(sync bool) {
 		// Use the surface as listener data for gio_onFrameDone.
 		C.wl_callback_add_listener(w.lastFrameCallback, &C.gio_callback_listener, unsafe.Pointer(w.surf))
 	}
-	cfg.now = time.Now()
 	w.w.Event(FrameEvent{
 		FrameEvent: system.FrameEvent{
+			Now: time.Now(),
 			Size: image.Point{
 				X: width,
 				Y: height,
diff --git a/app/internal/window/os_windows.go b/app/internal/window/os_windows.go
index 52dab973..41c0d079 100644
--- a/app/internal/window/os_windows.go
+++ b/app/internal/window/os_windows.go
@@ -370,9 +370,9 @@ func (w *window) draw(sync bool) {
 		return
 	}
 	cfg := configForDC()
-	cfg.now = time.Now()
 	w.w.Event(FrameEvent{
 		FrameEvent: system.FrameEvent{
+			Now: time.Now(),
 			Size: image.Point{
 				X: w.width,
 				Y: w.height,
diff --git a/app/internal/window/os_x11.go b/app/internal/window/os_x11.go
index 3d0b27e6..81cd370a 100644
--- a/app/internal/window/os_x11.go
+++ b/app/internal/window/os_x11.go
@@ -184,9 +184,9 @@ loop:
 		}
 
 		if anim || syn {
-			w.cfg.now = time.Now()
 			w.w.Event(FrameEvent{
 				FrameEvent: system.FrameEvent{
+					Now: time.Now(),
 					Size: image.Point{
 						X: w.width,
 						Y: w.height,
diff --git a/app/internal/window/window.go b/app/internal/window/window.go
index b52ece19..d3b30129 100644
--- a/app/internal/window/window.go
+++ b/app/internal/window/window.go
@@ -7,7 +7,6 @@ package window
 import (
 	"errors"
 	"math"
-	"time"
 
 	"gioui.org/gpu/backend"
 	"gioui.org/io/event"
@@ -78,11 +77,6 @@ type config struct {
 	pxPerDp float32
 	// Device pixels per sp.
 	pxPerSp float32
-	now     time.Time
-}
-
-func (c *config) Now() time.Time {
-	return c.now
 }
 
 func (c *config) Px(v unit.Value) int {
diff --git a/io/system/system.go b/io/system/system.go
index ac562633..4704789e 100644
--- a/io/system/system.go
+++ b/io/system/system.go
@@ -18,6 +18,9 @@ import (
 // input.
 type FrameEvent struct {
 	Config Config
+	// Now is the current animation. Use Now instead of time.Now to
+	// synchronize animation and to avoid the time.Now call overhead.
+	Now time.Time
 	// Size is the dimensions of the window.
 	Size image.Point
 	// Insets is the insets to apply.
@@ -51,9 +54,6 @@ type FrameEvent struct {
 // Config defines the essential properties of
 // the environment.
 type Config interface {
-	// Now returns the current animation time.
-	Now() time.Time
-
 	unit.Converter
 }
 
diff --git a/layout/context.go b/layout/context.go
index 2eda47a5..3c5c6393 100644
--- a/layout/context.go
+++ b/layout/context.go
@@ -24,6 +24,9 @@ type Context struct {
 	// By convention, a nil Queue is a signal to widgets to draw themselves
 	// in a disabled state.
 	Queue event.Queue
+	// Now is the animation time.
+	Now time.Time
+
 	*op.Ops
 }
 
@@ -31,6 +34,7 @@ type Context struct {
 //
 //   Context{
 //     Ops: ops,
+//     Now: e.Now,
 //     Queue: e.Queue,
 //     Config: e.Config,
 //     Constraints: Exact(e.Size),
@@ -41,20 +45,13 @@ func NewContext(ops *op.Ops, e system.FrameEvent) Context {
 	ops.Reset()
 	return Context{
 		Ops:         ops,
+		Now:         e.Now,
 		Queue:       e.Queue,
 		Config:      e.Config,
 		Constraints: Exact(e.Size),
 	}
 }
 
-// Now returns the configuration time or the zero time.
-func (c Context) Now() time.Time {
-	if c.Config == nil {
-		return time.Time{}
-	}
-	return c.Config.Now()
-}
-
 // Px maps the value to pixels. If no configuration is set,
 // Px returns the rounded value of v.
 func (c Context) Px(v unit.Value) int {
diff --git a/layout/list.go b/layout/list.go
index 243948f6..689a80ad 100644
--- a/layout/list.go
+++ b/layout/list.go
@@ -121,7 +121,7 @@ func (l *List) Dragging() bool {
 }
 
 func (l *List) update() {
-	d := l.scroll.Scroll(l.ctx, l.ctx, l.ctx.Now(), gesture.Axis(l.Axis))
+	d := l.scroll.Scroll(l.ctx, l.ctx, l.ctx.Now, gesture.Axis(l.Axis))
 	l.scrollDelta = d
 	l.Position.Offset += d
 }
diff --git a/widget/button.go b/widget/button.go
index 591431df..f5349204 100644
--- a/widget/button.go
+++ b/widget/button.go
@@ -80,7 +80,7 @@ func (b *Clickable) Layout(gtx layout.Context) layout.Dimensions {
 	stack.Pop()
 	for len(b.history) > 0 {
 		c := b.history[0]
-		if c.End.IsZero() || gtx.Now().Sub(c.End) < 1*time.Second {
+		if c.End.IsZero() || gtx.Now.Sub(c.End) < 1*time.Second {
 			break
 		}
 		n := copy(b.history, b.history[1:])
@@ -104,19 +104,19 @@ func (b *Clickable) update(gtx layout.Context) {
 				NumClicks: e.NumClicks,
 			})
 			if l := len(b.history); l > 0 {
-				b.history[l-1].End = gtx.Now()
+				b.history[l-1].End = gtx.Now
 			}
 		case gesture.TypeCancel:
 			for i := range b.history {
 				b.history[i].Cancelled = true
 				if b.history[i].End.IsZero() {
-					b.history[i].End = gtx.Now()
+					b.history[i].End = gtx.Now
 				}
 			}
 		case gesture.TypePress:
 			b.history = append(b.history, Press{
 				Position: e.Position,
-				Start:    gtx.Now(),
+				Start:    gtx.Now,
 			})
 		}
 	}
diff --git a/widget/editor.go b/widget/editor.go
index 27c5d640..91ac6eea 100644
--- a/widget/editor.go
+++ b/widget/editor.go
@@ -129,7 +129,7 @@ func (e *Editor) processPointer(gtx layout.Context) {
 		axis = gesture.Vertical
 		smin, smax = sbounds.Min.Y, sbounds.Max.Y
 	}
-	sdist := e.scroller.Scroll(gtx, gtx, gtx.Now(), axis)
+	sdist := e.scroller.Scroll(gtx, gtx, gtx.Now, axis)
 	var soff int
 	if e.SingleLine {
 		e.scrollRel(sdist, 0)
@@ -142,7 +142,7 @@ func (e *Editor) processPointer(gtx layout.Context) {
 		switch {
 		case evt.Type == gesture.TypePress && evt.Source == pointer.Mouse,
 			evt.Type == gesture.TypeClick && evt.Source == pointer.Touch:
-			e.blinkStart = gtx.Now()
+			e.blinkStart = gtx.Now
 			e.moveCoord(gtx, image.Point{
 				X: int(math.Round(float64(evt.Position.X))),
 				Y: int(math.Round(float64(evt.Position.Y))),
@@ -163,7 +163,7 @@ func (e *Editor) processKey(gtx layout.Context) {
 		e.events = append(e.events, ChangeEvent{})
 	}
 	for _, ke := range gtx.Events(&e.eventKey) {
-		e.blinkStart = gtx.Now()
+		e.blinkStart = gtx.Now
 		switch ke := ke.(type) {
 		case key.FocusEvent:
 			e.focused = ke.Focus
@@ -309,7 +309,7 @@ func (e *Editor) layout(gtx layout.Context) layout.Dimensions {
 	e.clicker.Add(gtx.Ops)
 	e.caretOn = false
 	if e.focused {
-		now := gtx.Now()
+		now := gtx.Now
 		dt := now.Sub(e.blinkStart)
 		blinking := dt < maxBlinkDuration
 		const timePerBlink = time.Second / blinksPerSecond
diff --git a/widget/material/button.go b/widget/material/button.go
index aa16be8d..be9c96a4 100644
--- a/widget/material/button.go
+++ b/widget/material/button.go
@@ -198,7 +198,7 @@ func drawInk(gtx layout.Context, c widget.Press) {
 		fadeDuration   = float32(0.9)
 	)
 
-	now := gtx.Now()
+	now := gtx.Now
 
 	t := float32(now.Sub(c.Start).Seconds())