Gradual log levels for Firefox trains

[larseggert]

#3025 demonstrates that we can (maybe) improve performance by a few percentage points by using release_max_level_off for log. That's obviously not something we can do, but I wonder if we could dom something like this:

• Set release_max_level_trace for Nightly.
• Set release_max_level_debug for Beta.
• Set release_max_level_info (or even release_max_level_warn?) for Release.

That disables progressively more logging, which should translate in some performance benefits. At the loss of logging. Worth it?

[mxinden]

Regarding #3025: wow, didn't expect such an impact.

Regarding the suggested changes, Firefox already implements a more aggressive version of it:

debug! and trace! logs will not appear in non-debug builds. This is due to our use of the release_max_level_info feature in the log crate.

https://firefox-source-docs.mozilla.org/testing-rust-code/index.html?utm_source=chatgpt.com#gecko-logging