Rust's performance benefits won't be immediate, as single-threaded C++ is already very fast and safe parallelism benefits of Rust would be difficult (impossible?) to leverage across language boundaries.
I'm more interested in seeing whether the maintainability of Firefox will increase over time as the proportion of Rust code increases. That is, will Mozilla be able to accelerate Firefox's development because the source code is in a safer language?
I'm more interested in seeing whether the maintainability of Firefox will increase over time as the proportion of Rust code increases. That is, will Mozilla be able to accelerate Firefox's development because the source code is in a safer language?