Cargo's debug profile is not "slower" for this library — it is unusable, and
it invalidated every on-device performance test to date: RustCrypto's AES-GCM
compiles to generic-array iterator closures with per-byte precondition checks
instead of ARMv8 hardware AES. Profiled live on a phone (simpleperf, 62k
samples): ~800 µs of user CPU per 1.4 KB packet — the receive pump pinned
above a full core yet only draining ~1,400 pkt/s of a 1,775 pkt/s (20 Mbps)
stream, 2.3 MB standing in the kernel socket buffer, the latency-bound flush
firing every 2 s forever. With release rust in the same debug APK: pump at
~12 % of a core, socket queue zero, no flushes, 2800x1260@120 streaming clean.
preDebugBuild now depends on cargoNdkRelease; `-PrustDebug` opts back into a
debug-profile native build for sessions that actually step through Rust.
Kotlin debuggability is unchanged.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
17685ff73b