Hello
Thank you for your question and reaching out. I can understand you are having query\issues related to LSASS taking huge time.
- Please check and scan for Check for malware and also perform Full scan with your Antivirus on 2012 R2 server.
- Disable any Local Windows firewall for temporary purpose.
- Perform scandisk using below command as some due to disk issues it may tame take time to boot up.
chkdsk /f /r c:\
- Please also consider to Migrate FSMO role to new Additional DC having 2019 or 2022 installed.
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