Please follow the below steps and restart the server and see if the helps.
Click START and type IIS
Expand your server
Expand APPLICATION POOLS
Click on WSUSPOOL and select ADVANCED SETTINGS from the action pane on the right
Scroll down and set PRIVATE MEMORY LIMIT to a higher limit (I doubled mine)
Set REGULAR TIME INTERVAL to a lower limit (I set mine to about half so it automatically cycles more often)
Click OK on the ADVANCED SETTING dialog
Right click on WSUSPOOL and select START
Click RESET SERVER NODE or restart the server
Hope this resolves your Query !!
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