message: Put speed holes in the code
  We can make read receipts more efficient (and avoid double-animation) by using `PureComponent` which no-ops useless updates for us.
diff: @@ -32,7 +32,7 @@ try {
  } catch (e) {
  }
  -export default class ReadReceiptMarker extends React.Component {
  +export default class ReadReceiptMarker extends React.PureComponent {
  static propTypes = {
  // the RoomMember to show the RR for
  member: PropTypes.object,
  