diff --git a/Cargo.toml b/Cargo.toml
index e7f85485a..98cce445d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,3 +25,62 @@ members = [
 	"lib-orml/utilities",
 ]
 exclude = ['rpc']
+
+# The list of dependencies below (which can be both direct and indirect dependencies) are crates
+# that are suspected to be CPU-intensive, and that are unlikely to require debugging (as some of
+# their debug info might be missing) or to require to be frequently recompiled. We compile these
+# dependencies with `opt-level=3` even in "dev" mode in order to make "dev" mode more usable.
+# The majority of these crates are cryptographic libraries.
+#
+# Note that this does **not** affect crates that depend on Substrate. In other words, if you add
+# a dependency on Substrate, you have to copy-paste this list in your own `Cargo.toml` (assuming
+# that you want the same list). This list is only relevant when running `cargo build` from within
+# the Substrate workspace.
+#
+# If you see an error mentioning "profile package spec ... did not match any packages", it
+# probably concerns this list.
+#
+# This list is ordered alphabetically.
+[profile.dev.package]
+blake2 = { opt-level = 3 }
+blake2-rfc = { opt-level = 3 }
+blake2b_simd = { opt-level = 3 }
+chacha20poly1305 = { opt-level = 3 }
+cranelift-codegen = { opt-level = 3 }
+cranelift-wasm = { opt-level = 3 }
+crc32fast = { opt-level = 3 }
+crossbeam-deque = { opt-level = 3 }
+crypto-mac = { opt-level = 3 }
+curve25519-dalek = { opt-level = 3 }
+ed25519-dalek = { opt-level = 3 }
+flate2 = { opt-level = 3 }
+futures-channel = { opt-level = 3 }
+hashbrown = { opt-level = 3 }
+hash-db = { opt-level = 3 }
+hmac = { opt-level = 3 }
+httparse = { opt-level = 3 }
+integer-sqrt = { opt-level = 3 }
+keccak = { opt-level = 3 }
+libm = { opt-level = 3 }
+librocksdb-sys = { opt-level = 3 }
+libsecp256k1 = { opt-level = 3 }
+libz-sys = { opt-level = 3 }
+mio = { opt-level = 3 }
+nalgebra = { opt-level = 3 }
+num-bigint = { opt-level = 3 }
+parking_lot = { opt-level = 3 }
+parking_lot_core = { opt-level = 3 }
+percent-encoding = { opt-level = 3 }
+primitive-types = { opt-level = 3 }
+ring = { opt-level = 3 }
+rustls = { opt-level = 3 }
+sha2 = { opt-level = 3 }
+sha3 = { opt-level = 3 }
+smallvec = { opt-level = 3 }
+snow = { opt-level = 3 }
+twox-hash = { opt-level = 3 }
+uint = { opt-level = 3 }
+wasmi = { opt-level = 3 }
+x25519-dalek = { opt-level = 3 }
+yamux = { opt-level = 3 }
+zeroize = { opt-level = 3 }