Debug Build Performance

Debug builds run much slower than release builds. For per-frame work that crosses the Rust/Godot boundary many times -- transform sync over hundreds of nodes, for example -- a debug build can be several times slower than release. This is normal, and most of the gap comes from two independent causes you can tune separately.

Optimize your dependencies

By default a debug build compiles everything at opt-level = 0, including Bevy, gdext, and the rest of your dependency tree. Those crates do the heavy per-frame math, so leaving them unoptimized is what makes debug builds feel sluggish.

Optimize your dependencies while leaving your own crate unoptimized:

[profile.dev.package."*"]
opt-level = 3

Your own code still compiles quickly and stays fully debuggable, while the hot paths in your dependencies run at release speed. In transform-heavy scenes this is worth roughly a 3x improvement. It is standard Rust practice rather than anything specific to godot-bevy -- the Bevy book recommends the same setting. The godot-bevy project wizard scaffolds it into your Cargo.toml automatically.

Tune gdext safeguards

gdext runs runtime validity checks on calls that cross the FFI boundary. These catch real bugs (use-after-free, type mismatches) but add per-call overhead. gdext exposes three levels:

• Strict -- default for dev builds, maximum checking.
• Balanced -- default for release builds, basic validity checks, fast.
• Disengaged -- most checks off, fastest, unsafe.

If FFI validation shows up in your profile, drop the dev level to balanced:

godot = { version = "0.x", features = ["safeguards-dev-balanced"] }

There is a matching safeguards-release-disengaged for shipping builds, but only reach for it after testing thoroughly on a higher level. See gdext's safeguard levels documentation for details.