Why Xcode12.3 takes up more than 18GB of RAM

Why Xcode12.3 takes up more than 18GB of RAM?
I just checked in Monitor.

With a mid size project opened, it uses 156 MB "only".

Where do you measure 18 GB ?
Do you really speak of RAM or of disk space ?
RAM 10 ~ 18GB
Disk almost 64GB
Why Xcode12.3 takes up more than 18GB of RAM
 
 
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