One major selling point for C++ for new projects is efficiency. People are still skeptical that other languages can truly compete with C++ in that space. For example, people that need low latency (game development, trading, etc.) or are into HPC, may never be convinced to switch away from C++ because of this reason. We still don’t have enough data to argue if another language that provides safety can compete with C++ in this area.

While I can agree we don’t have sufficient data to make hard conclusions on this front, I think there are enough early indications that point to Rust being able to stay on par with or even outperform C++ in this regard:

• Google, Firefox and Microsoft report performance improvements from migration to Rust. Some of this was attributable to having a better understanding of the problem domain upfront, thus giving an opportunity to choose better data structures. But a large part was also because choosing Rust obsoleted the need for other safety techniques that had a higher runtime impact, such as Google’s MiraclePtr or even sandboxing.
• Crypto-traders have already massively adopted Rust as their language of choice, providing evidence the language is fast enough for their use cases. It seems a matter of time before traditional traders make the switch.
• Rust ownership model avoids issues with possible memory aliasing that are inherent in C and C++. This enables compilers to apply optimizations they cannot apply otherwise, leading to higher theoretical throughput. Meanwhile, areas where Rust is theoretically slower (such as mandated bounds checking) are also applicable to C++ whenever safety is prioritized.