How to solve lsass.exe very high ram usage?
Solution 1:
On my system, lsass.exe is consuming about 10K.
I'm at work. On our company's main domain controller, lsass.exe is up to about 80K.
Either your lsass.exe is infected, a piece of malware is trying to do something funny, or (least likely) something over the network is trying to do the same.
It's also possible you may have a legitimate program making a legitimate amount of authentication requests - possibly something running as another user accessing many, many files in a short period of time or similar.