What cyber attacks could be reasons behing the below symptoms of workstation running windows $11?$

$1.$ Application startup time has increased significantly $(5-10$ minutes$).$

$2.$ Users experience random freezes when generating reports with large datasets.

$3.$ No issues reported on other non$-$affected workstations running the same application version.

$4.$ CPU usage on affected systems spikes to $90\%+$ while using the application.