New Post: SPServices and jQuery 1.10 (and beyond)

Good info.

A few suggestions that may help speed things up.

- append items to DOM every 1000 rows. Maybe even less if it makes a difference.

- use native DOM methods to append rather than jQuery wrapper. I don't think it will matters, but worth a try. Something like:

$("#users_SiteUsers")[0].html = strHTML;

Or maybe a detached DocumentFragment and keep appending the items to it. Then, in the end, just append/attach the fragment to DOM.

- any chance you can use a widget to present your list if items rather than a Select element? Something with an AutoComplete type of UI? That way you don't have to load up so many DOM elements at once. I see you are working with users. Maybe this widget could help (disclosure: I'm the creator of it): people picker - https://github.com/purtuga/SPWidgets/blob/master/documentation/SPWidgets.pickSPUser.md (http://purtuga.github.com/SPWidgets/)

Hope this helps. Good luck.