diff --git a/Cargo.lock b/Cargo.lock
index 4066036..6ee77c2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -53,6 +53,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "anes"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
+
 [[package]]
 name = "anstream"
 version = "0.6.15"
@@ -305,6 +311,7 @@ dependencies = [
  "axum-extra",
  "blah-types",
  "clap",
+ "criterion",
  "ed25519-dalek",
  "futures-util",
  "hex",
@@ -361,6 +368,12 @@ version = "1.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8318a53db07bb3f8dca91a600466bdb3f2eaadeedfdbcf02e1accbad9271ba50"
 
+[[package]]
+name = "cast"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
+
 [[package]]
 name = "cc"
 version = "1.1.14"
@@ -395,6 +408,33 @@ dependencies = [
  "windows-targets",
 ]
 
+[[package]]
+name = "ciborium"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42e69ffd6f0917f5c029256a24d0161db17cea3997d185db0d35926308770f0e"
+dependencies = [
+ "ciborium-io",
+ "ciborium-ll",
+ "serde",
+]
+
+[[package]]
+name = "ciborium-io"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05afea1e0a06c9be33d539b876f1ce3692f4afea2cb41f740e7743225ed1c757"
+
+[[package]]
+name = "ciborium-ll"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57663b653d948a338bfb3eeba9bb2fd5fcfaecb9e199e87e1eda4d9e8b240fd9"
+dependencies = [
+ "ciborium-io",
+ "half",
+]
+
 [[package]]
 name = "clap"
 version = "4.5.16"
@@ -472,6 +512,73 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "criterion"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2b12d017a929603d80db1831cd3a24082f8137ce19c69e6447f54f5fc8d692f"
+dependencies = [
+ "anes",
+ "cast",
+ "ciborium",
+ "clap",
+ "criterion-plot",
+ "is-terminal",
+ "itertools",
+ "num-traits",
+ "once_cell",
+ "oorandom",
+ "plotters",
+ "rayon",
+ "regex",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "tinytemplate",
+ "walkdir",
+]
+
+[[package]]
+name = "criterion-plot"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b50826342786a51a89e2da3a28f1c32b06e387201bc2d19791f622c673706b1"
+dependencies = [
+ "cast",
+ "itertools",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "613f8cc01fe9cf1a3eb3d7f488fd2fa8388403e97039e2f73692932e291a770d"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22ec99545bb0ed0ea7bb9b8e1e9122ea386ff8a48c0922e43f36d45ab09e0e80"
+
+[[package]]
+name = "crunchy"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a81dae078cea95a014a339291cec439d2f232ebe854a9d672b796c6afafa9b7"
+
 [[package]]
 name = "crypto-common"
 version = "0.1.6"
@@ -612,6 +719,12 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
 [[package]]
 name = "encoding_rs"
 version = "0.8.34"
@@ -806,6 +919,16 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "half"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6dd08c532ae367adf81c312a4580bc67f1d0fe8bc9c460520283f4c0ff277888"
+dependencies = [
+ "cfg-if",
+ "crunchy",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.12.3"
@@ -842,6 +965,12 @@ version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
 
+[[package]]
+name = "hermit-abi"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fbf6a919d6cf397374f7dfeeea91d974c7c0a7221d0d0f4f20d859d329e53fcc"
+
 [[package]]
 name = "hex"
 version = "0.4.3"
@@ -1053,12 +1182,32 @@ version = "2.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f518f335dce6725a761382244631d86cf0ccb2863413590b31338feb467f9c3"
 
+[[package]]
+name = "is-terminal"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "261f68e344040fbd0edea105bef17c66edf46f984ddb1115b775ce31be948f4b"
+dependencies = [
+ "hermit-abi 0.4.0",
+ "libc",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "is_terminal_polyfill"
 version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
+[[package]]
+name = "itertools"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.11"
@@ -1151,7 +1300,7 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "80e04d1dcff3aae0704555fe5fee3bcfaf3d1fdf8a7e521d5b9d2b42acb52cec"
 dependencies = [
- "hermit-abi",
+ "hermit-abi 0.3.9",
  "libc",
  "wasi",
  "windows-sys 0.52.0",
@@ -1226,6 +1375,12 @@ version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
 
+[[package]]
+name = "oorandom"
+version = "11.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b410bbe7e14ab526a0e86877eb47c6996a2bd7746f027ba551028c925390e4e9"
+
 [[package]]
 name = "openssl"
 version = "0.10.66"
@@ -1362,6 +1517,34 @@ version = "0.3.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d231b230927b5e4ad203db57bbcbee2802f6bce620b1e4a9024a07d94e2907ec"
 
+[[package]]
+name = "plotters"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5aeb6f403d7a4911efb1e33402027fc44f29b5bf6def3effcc22d7bb75f2b747"
+dependencies = [
+ "num-traits",
+ "plotters-backend",
+ "plotters-svg",
+ "wasm-bindgen",
+ "web-sys",
+]
+
+[[package]]
+name = "plotters-backend"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df42e13c12958a16b3f7f4386b9ab1f3e7933914ecea48da7139435263a4172a"
+
+[[package]]
+name = "plotters-svg"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51bae2ac328883f7acdfea3d66a7c35751187f870bc81f94563733a154d7a670"
+dependencies = [
+ "plotters-backend",
+]
+
 [[package]]
 name = "powerfmt"
 version = "0.2.0"
@@ -1425,6 +1608,26 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "rayon"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b418a60154510ca1a002a752ca9714984e21e4241e804d32555251faf8b78ffa"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1465873a3dfdaa8ae7cb14b4383657caab0b3e8a0aa9ae8e04b044854c8dfce2"
+dependencies = [
+ "crossbeam-deque",
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.5.3"
@@ -1654,6 +1857,15 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6518fc26bced4d53678a22d6e423e9d8716377def84545fe328236e3af070e7f"
 
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "schannel"
 version = "0.1.23"
@@ -2048,6 +2260,16 @@ dependencies = [
  "time-core",
 ]
 
+[[package]]
+name = "tinytemplate"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be4d6b5f19ff7664e8c98d03e2139cb510db9b0a60b55f8e8709b689d939b6bc"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "tinyvec"
 version = "1.8.0"
@@ -2390,6 +2612,16 @@ version = "0.9.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
 
+[[package]]
+name = "walkdir"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29790946404f91d9c5d06f9874efddea1dc06c5efe94541a7d6863108e3a5e4b"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
 [[package]]
 name = "want"
 version = "0.3.1"
@@ -2498,6 +2730,15 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 
+[[package]]
+name = "winapi-util"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
+dependencies = [
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "winapi-x86_64-pc-windows-gnu"
 version = "0.4.0"
diff --git a/Cargo.toml b/Cargo.toml
index 26683d4..e4d18f9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,3 +14,6 @@ print_stderr = "warn"
 print_stdout = "warn"
 todo = "warn"
 unwrap_used = "warn"
+
+[profile.bench]
+debug = "line-tables-only"
diff --git a/blahd/Cargo.toml b/blahd/Cargo.toml
index 0504916..a113186 100644
--- a/blahd/Cargo.toml
+++ b/blahd/Cargo.toml
@@ -3,6 +3,10 @@ name = "blahd"
 version = "0.0.0"
 edition = "2021"
 
+[[bench]]
+name = "register-pow"
+harness = false
+
 [dependencies]
 anyhow = "1"
 axum = { version = "0.7", features = ["ws"] }
@@ -36,6 +40,7 @@ url = { version = "2.5.2", features = ["serde"] }
 blah-types = { path = "../blah-types", features = ["rusqlite"] }
 
 [dev-dependencies]
+criterion = "0.5"
 nix = { version = "0.29.0", features = ["fs", "process", "signal"] }
 reqwest = { version = "0.12.7", features = ["json"] }
 rstest = { version = "0.22.0", default-features = false }
diff --git a/blahd/benches/register-pow.rs b/blahd/benches/register-pow.rs
new file mode 100644
index 0000000..f1d9560
--- /dev/null
+++ b/blahd/benches/register-pow.rs
@@ -0,0 +1,56 @@
+#![expect(clippy::unwrap_used, reason = "allow in benches")]
+use std::hint::black_box;
+use std::time::Instant;
+
+use blah_types::{get_timestamp, PubKey, Signee, UserKey, UserRegisterPayload};
+use criterion::{criterion_group, criterion_main, Criterion};
+use ed25519_dalek::SigningKey;
+use rand::{thread_rng, Rng};
+use sha2::{Digest, Sha256};
+
+fn bench_register_pow(c: &mut Criterion) {
+    let rng = &mut thread_rng();
+
+    let id_key_priv = SigningKey::from_bytes(&[0x1A; 32]);
+    let id_key = PubKey(id_key_priv.verifying_key().to_bytes());
+    let act_key_priv = SigningKey::from_bytes(&[0x2B; 32]);
+    let act_key = PubKey(act_key_priv.verifying_key().to_bytes());
+    let payload = UserRegisterPayload {
+        id_key: id_key.clone(),
+        server_url: "http://some.example.com".parse().unwrap(),
+        id_url: "http://another.example.com".parse().unwrap(),
+        challenge_nonce: rng.gen(),
+    };
+    let mut signee = Signee {
+        nonce: 0,
+        payload,
+        timestamp: get_timestamp(),
+        user: UserKey { id_key, act_key },
+    };
+
+    c.bench_function("register_pow_iter", |b| {
+        b.iter_custom(|iters| {
+            signee.nonce = rng.gen();
+
+            let inst = Instant::now();
+            for _ in 0..iters {
+                let hash = {
+                    let signee = serde_jcs::to_string(&signee).unwrap();
+                    let mut h = Sha256::new();
+                    h.update(&signee);
+                    h.finalize()
+                };
+                let leading_zeros = hash
+                    .iter()
+                    .position(|&b| b != 0)
+                    .map_or(256, |i| i as u32 * 8 + hash[i].leading_zeros());
+                black_box(leading_zeros);
+                signee.nonce = signee.nonce.wrapping_add(1);
+            }
+            inst.elapsed()
+        });
+    });
+}
+
+criterion_group!(benches, bench_register_pow);
+criterion_main!(benches);