So, the issue is that no matter what sort of Processor/Graphics card you are running, the login screen/disconnect screen for UO can eat the living crap out of your CPU, especially when running multiple clients at once. Event sleep was the old way to get around this which allowed you to reduce the cpu usage down to 0% For a period of Time.
The Easiest solution I can see so far is to Login to a different server and at the Character Selection/Creation Page, you can see whether or not you are on the wrong server or not with #Lshard, you can stay on that page for about 15 minutes, then you Attempt to force #lshard to what you want to be and go back to the shard selection page, and repeat until you get into the shard you want.
; if you are on the Character Selection page or the Character Creation page and its not the right shard.
if #Contsize = 640_480 && ( #Contname = Login_Gump || #Contname = CharCreation_Gump ) && #Lshard <> !Shard
{
wait 16000 ; <- 15 Minutes
set #lshard !Shard ; <- Put the shard back to the Shard # that you want it to be.
Click 595 445 ; <- Pops you back to the Shard Selection
wait 40
}