<!-- Is your issue related solely to the core library, or is your issue related to an extension? An extension issue must be filed in the extension's repo. --> **Issue type** <!-- Are you submitting a bug report or a feature request? When submitting a bug report, check the following: - The report has a descriptive title. - The bug still exists in most recent version of the library. A request for help or a requests for a how-to should be directed to Stack Overflow: http://stackoverflow.com/questions/tagged/cytoscape.js --> <!-- Delete one option --> Feature request <!-- FEATURE REQUEST : Delete if reporting a bug --> **Description of new feature** <!-- What should the new feature do? For visual features, include an image/mockup of the expected output. --> For collection listener functions, a common `Selector` object should be made per call --- rather than per element. **Motivation for new feature** <!-- Describe your use case for this new feature. --> Performance <!-- END FEATURE REQUEST -->