Actually yes, in an open source ecosystem the onus is on you to show that a change is making things worse for you. You can't expect the developers to test on all systems.
I'm not asking to test on any system EXCEPT THEIR OWN. Did they test the performance of not? If not, fine. That's all I was asking. It's not a huge ask either unless they don't give a rat's ass about performance. Which, if they want to use C++, they most likely do not.