diff --git a/Cargo.toml b/Cargo.toml
index bd248f14..80157078 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -51,6 +51,18 @@ opt-level = 1
 [profile.release]
 panic = "abort"
 
+# Speed up release builds and sync tests using link-time optimization.
+# Some of Zebra's code is CPU-intensive, and needs extra optimizations for peak performance.
+#
+# TODO:
+# - add "-Clinker-plugin-lto" in .cargo/config.toml to speed up release builds
+#     - add "-Clinker=clang -Clink-arg=-fuse-ld=lld" in .cargo/config.toml
+# - also use LTO on C/C++ code:
+#     - use clang to compile all C/C++ code
+#     - add "-flto=thin" to all C/C++ code builds
+#     - see https://doc.rust-lang.org/rustc/linker-plugin-lto.html#cc-code-as-a-dependency-in-rust
+lto = "thin"
+
 [patch.crates-io]
 
 # TODO: replace with upstream librustzcash when these changes are merged (#3037)
diff --git a/docker/Dockerfile b/docker/Dockerfile
index f2e034a2..55f7e5f4 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -42,12 +42,6 @@ RUN if [ "$(uname -m)" != "aarch64" ]; then \
     && \
     rm -rf /var/lib/apt/lists/* /tmp/*
 
-# Optimize builds. In particular, regenerate-stateful-test-disks.yml was reaching the
-# GitHub Actions time limit (6 hours), so we needed to make it faster.
-#
-# TODO: apply this optimisation level to all release builds in .cargo/config.toml
-ENV RUSTFLAGS "-C opt-level=3"
-
 ENV CARGO_HOME /app/.cargo/
 # Build dependencies - this is the caching Docker layer!
 RUN cargo chef cook --release --features enable-sentry --recipe-path recipe.json