optimize notification icon caching by copying image rather than item

Modules/Dock/Wrapper.qml

@@ -9,18 +9,17 @@ Item {
 	id: root
 
 	property int contentHeight
+	property real offsetScale: shouldBeActive ? 0 : 1
 	required property var panels
 	required property ShellScreen screen
+	readonly property bool shouldBeActive: visibilities.dock && Config.dock.enable
 	required property PersistentProperties visibilities
 
-	readonly property bool shouldBeActive: visibilities.dock
-	property real offsetScale: shouldBeActive ? 0 : 1
-
-	visible: offsetScale < 1
 	anchors.bottomMargin: (-implicitHeight - 5) * offsetScale
 	implicitHeight: content.implicitHeight
 	implicitWidth: content.implicitWidth || 400
 	opacity: 1 - offsetScale
+	visible: offsetScale < 1
 
 	Behavior on offsetScale {
 		Anim {
@@ -32,10 +31,10 @@ Item {
 	Loader {
 		id: content
 
+		active: root.shouldBeActive || root.visible
 		anchors.left: parent.left
 		anchors.top: parent.top
-
-		active: root.shouldBeActive || root.visible
+		asynchronous: true
 
 		sourceComponent: Content {
 			panels: root.panels