The problem in this case is not the potential performance bottleneck, but the bad ergonomics for a dev, that leads to the complain. The rest is consequence.
And to me it looks like pure language/stdlib problem. Like for me, the proposed solution looks ugly both from syntax and what is going on behind curtains perspective.
I would rather not to code in a language that makes/tolerates decisions like that.
I mean if this one thing is enough to turn you off, you do you. I find GDScript to be 98% good for a dynamic scripting language.
Personally I’d just reverse the array and then iterate it. It’s going to make about zero difference.
Every language has its sharp edges.
I would imagine for most games the performance impact from this won’t matter much.