Might be related to #15078
When a selectmenu is initialised , an internally used <span> section is created that contain button , icon and text.
Each of the components has a set of event listeners .
The bug is - after any activity on a selectmenu ( such as selecting options, just clicking on the menu button a few times, calling .selectmenu("refresh") )
a bunch of 'remove' event handlers gets added to the the selectmenu button.
Looks like the number of the added handlers is equal to the number of menu options.
I.e. if a selectmenu has 10 options , clicking on a menu 3 times adds 30 identical handlers to the menu button.
Observed with jQueryUI 1.12.1 and jQuery 1.12.4 and 3.1.1
Easy to reproduce - just load an example page ( like http://jqueryui.com/selectmenu ) , click the selectmenu button a few times , then inspect the button event handlers list .
May ( and most likely does ) cause general slow downs due to memory/cpu starvation.