When I click a search for a user in a workflow, becomes too slow and getting the below error

"A script on this page may be busy, or it may have stopped responding. You can stop the script now, open the script in the debugger, or let the script continue.

Script: https://userappdev.xxx.du/IDMProv/UIQuery?js=JUICE.js:5936"

Do we have an option to set the heap size in user application? Please let me know the ways to overcome this slowness issue. Please assist.