Some sacrifices were made... But the end result is a Godot project that works exactly the same, albeit with slightly worse performance.
The write up has lots of hard numbers for the executable size but only describes the performance impact in general terms.
It would be good to see some before and after performance numbers.
It can be fun to go to an achievement/trophy tracker and compare the numbers for the awards for first and last story missions.
For GTA5 some numbers are:
For Assassins Creed Odyssey: