Antimalware Service Executable: High RAM usage

First Solution: Add Antimalware Service Executable to Windows Defender exclusion list

1) Hold down the Windows key and press the I keys to open Settings.
2) Proceed to click on “Update & Security” and then select “Windows Security”.
3) Click on the option “Virus and threat protection”.
4) Under Virus & threat protection settings, you’ll want to click on the option “Manage settings”.
5) Scroll down and look for Exclusions and select Add or remove exclusions.
6) Click on “Add an exclusion and select Process” and add the Antimalware Service Executable to the list. Below is linked its .exe file.
Type MsMpEng.exe and click on Add.

Second Solution:

1) Hold down the Windows key and press R, to open the “Run” dialog box
2) Type taskschd.msc and click on OK.
3) Now expand Task Scheduler Library then select Microsoft then select Windows
4) Select Windows Defender and on the right-hand pane double-click on Windows Defender Scheduled Scan.
5) Under the General tab, uncheck the box next to Run with the highest privileges.
6) Select the Conditions tab, uncheck all the items, and click on OK.