diff --git a/internal/graphics/command.go b/internal/graphics/command.go
index 2f9e120f8..c11a0c226 100644
--- a/internal/graphics/command.go
+++ b/internal/graphics/command.go
@@ -49,13 +49,14 @@ func (q *commandQueue) appendVertices(vertices []float32) {
 }
 
 func (q *commandQueue) EnqueueDrawImageCommand(dst, src *Image, vertices []float32, clr *affine.ColorM, mode opengl.CompositeMode) {
+	// Avoid defer for performance
 	q.m.Lock()
-	defer q.m.Unlock()
 	q.appendVertices(vertices)
 	if 0 < len(q.commands) {
 		if c, ok := q.commands[len(q.commands)-1].(*drawImageCommand); ok {
 			if c.isMergeable(dst, src, clr, mode) {
 				c.verticesNum += len(vertices)
+				q.m.Unlock()
 				return
 			}
 		}
@@ -68,12 +69,13 @@ func (q *commandQueue) EnqueueDrawImageCommand(dst, src *Image, vertices []float
 		mode:        mode,
 	}
 	q.commands = append(q.commands, c)
+	q.m.Unlock()
 }
 
 func (q *commandQueue) Enqueue(command command) {
 	q.m.Lock()
-	defer q.m.Unlock()
 	q.commands = append(q.commands, command)
+	q.m.Unlock()
 }
 
 // commandGroups separates q.commands into some groups.
diff --git a/internal/restorable/images.go b/internal/restorable/images.go
index 116816350..67f8a0640 100644
--- a/internal/restorable/images.go
+++ b/internal/restorable/images.go
@@ -66,19 +66,22 @@ func (i *images) resolveStalePixels(context *opengl.Context) error {
 }
 
 func (i *images) resetPixelsIfDependingOn(target *Image) {
+	// Avoid defer for performance
 	i.m.Lock()
-	defer i.m.Unlock()
 	if target == nil {
 		// disposed
+		i.m.Unlock()
 		return
 	}
 	if i.lastChecked == target {
+		i.m.Unlock()
 		return
 	}
 	i.lastChecked = target
 	for img := range i.images {
 		img.makeStaleIfDependingOn(target)
 	}
+	i.m.Unlock()
 }
 
 func (i *images) restore(context *opengl.Context) error {