> Font shaping performance increased by 5-15% compared to the C++ version.
Personally, I wouldn't link it directly to rust, but to rewriting. When you develop something, you usually can't account for all future changes that affect performance, design, LOC, robustness, and so on. But with rewrite, you take them all into account. So there is a big chance that rewrite will be superior in many areas. It will probably have the same effect as if they had rewritten it in C++ again.
Personally, I wouldn't link it directly to rust, but to rewriting. When you develop something, you usually can't account for all future changes that affect performance, design, LOC, robustness, and so on. But with rewrite, you take them all into account. So there is a big chance that rewrite will be superior in many areas. It will probably have the same effect as if they had rewritten it in C++ again.