Is sorting slow for you in UltraEdit? It takes over 10 seconds to sort a 100 line file for me. The last few releases of UltraEdit has had this problem.
I sorted an ANSI encoded XML file with more than 6000 lines with UE v24.20 with default settings (configuration and sort settings) within a second. In other words the displayed refreshed immediately with showing the sorted lines after clicking on sort item.
I'm using UltraEdit already for more than 15 years. I have never seen a sort taking longer than a second on sorting less than 10000 lines. I think this is true also for nearly all other users of UltraEdit.
I suggest to use free Process Monitor of Sysinternals (Microsoft) to find out what makes the sort so slow on your machine.
I cannot help better without having the file to sort, your UltraEdit configuration, knowing the used sort options and the steps you execute resulting in the slow sort.