Just popped open Task Manager...

calculator.exe is at 74 MB working set, 24 MB Memory (private set), 50 MB Memory (shared working set), 48 MB commit size.

mIRC.exe is at 31 MB working set, 13 MB Memory (private set), 18 MB Memory (shared working set), 38 MB commit size.

Doesn't matter which value you use for "How much memory does this program use?". mIRC is smaller in all of them.

That's not `calc.exe`. I think windows doesn't ship with calc.exe anymore. The fair comparison would be the last version of mIRC that was current when the last version of calc.exe was shipped. I don't believe that mIRC would use less RAM than that... Certainly not when you were actually USING it! (including reconfiguring the size of your scrollback, for example..)

You can still get it from https://win7games.com/#calc (via WinAero).

The OG calc.exe still ships with the LTS[B,C] versions of Windows 10.

Which tells you the new version is anti-privacy.