diff --git a/Cargo.lock b/Cargo.lock
index 61fa7f7..ce107a3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,12 +2,36 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddd31a130427c27518df266943a5308ed92d4b226cc639f5a8f1002816174301"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "alloca"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5a7d05ea6aea7e9e64d25b9156ba2fee3fdd659e34e41063cd2fc7cd020d7f4"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "allocator-api2"
 version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
 
+[[package]]
+name = "anes"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
+
 [[package]]
 name = "anstream"
 version = "0.6.19"
@@ -123,6 +147,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "bumpalo"
+version = "3.20.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d20789868f4b01b2f2caec9f5c4e0213b41e3e5702a50157d699ae31ced2fcb"
+
 [[package]]
 name = "bytemuck"
 version = "1.23.1"
@@ -144,6 +174,12 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "cast"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
+
 [[package]]
 name = "cc"
 version = "1.2.27"
@@ -161,6 +197,33 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9555578bc9e57714c812a1f84e4fc5b4d21fcb063490c624de019f7464c91268"
 
+[[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 = "4.5.60"
@@ -253,6 +316,41 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "criterion"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "950046b2aa2492f9a536f5f4f9a3de7b9e2476e575e05bd6c333371add4d98f3"
+dependencies = [
+ "alloca",
+ "anes",
+ "cast",
+ "ciborium",
+ "clap",
+ "criterion-plot",
+ "itertools",
+ "num-traits",
+ "oorandom",
+ "page_size",
+ "plotters",
+ "rayon",
+ "regex",
+ "serde",
+ "serde_json",
+ "tinytemplate",
+ "walkdir",
+]
+
+[[package]]
+name = "criterion-plot"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8d80a2f4f5b554395e47b5d8305bc3d27813bacb73493eb1001e8f76dae29ea"
+dependencies = [
+ "cast",
+ "itertools",
+]
+
 [[package]]
 name = "crossbeam"
 version = "0.8.4"
@@ -345,6 +443,12 @@ dependencies = [
  "nu-ansi-term",
 ]
 
+[[package]]
+name = "crunchy"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
+
 [[package]]
 name = "crypto-common"
 version = "0.1.6"
@@ -1496,6 +1600,17 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "half"
+version = "2.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ea2d84b969582b4b1864a92dc5d27cd2b77b622a8d79306834f1be5ba20d84b"
+dependencies = [
+ "cfg-if",
+ "crunchy",
+ "zerocopy",
+]
+
 [[package]]
 name = "hash32"
 version = "0.3.1"
@@ -1735,6 +1850,15 @@ version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
+[[package]]
+name = "itertools"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.17"
@@ -1753,7 +1877,7 @@ dependencies = [
  "portable-atomic",
  "portable-atomic-util",
  "serde_core",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -1792,6 +1916,16 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "js-sys"
+version = "0.3.91"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b49715b7073f385ba4bc528e5747d02e66cb39c6146efb66b781f131f0fb399c"
+dependencies = [
+ "once_cell",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "jwalk"
 version = "0.8.1"
@@ -1962,7 +2096,16 @@ version = "0.50.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
 dependencies = [
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
 ]
 
 [[package]]
@@ -1977,6 +2120,12 @@ version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a4895175b425cb1f87721b59f0f286c2092bd4af812243672510e1ac53e2e0ad"
 
+[[package]]
+name = "oorandom"
+version = "11.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6790f58c7ff633d8771f42965289203411a5e5c68388703c06e14f24770b41e"
+
 [[package]]
 name = "open"
 version = "5.3.2"
@@ -2006,6 +2155,16 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "page_size"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "30d5b2194ed13191c1999ae0704b7839fb18384fa22e49b57eeaa97d79ce40da"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
 [[package]]
 name = "parking_lot"
 version = "0.12.4"
@@ -2047,6 +2206,34 @@ version = "0.3.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7edddbd0b52d732b21ad9a5fab5c704c14cd949e5e9a1ec5929a24fded1b904c"
 
+[[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 = "portable-atomic"
 version = "1.11.1"
@@ -2137,11 +2324,34 @@ dependencies = [
  "bitflags",
 ]
 
+[[package]]
+name = "regex"
+version = "1.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23d7fd106d8c02486a8d64e778353d1cffe08ce79ac2e82f540c86d0facf6912"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
 [[package]]
 name = "regex-automata"
 version = "0.4.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc897dd8d9e8bd1ed8cdad82b5966c3e0ecae09fb1907d58efaa013543185d0a"
 
 [[package]]
 name = "rustix"
@@ -2153,7 +2363,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -2340,6 +2550,7 @@ dependencies = [
  "clap",
  "clap_complete",
  "clap_complete_nushell",
+ "criterion",
  "figment",
  "git2",
  "gitoxide-core",
@@ -2387,7 +2598,7 @@ dependencies = [
  "getrandom",
  "once_cell",
  "rustix",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -2430,6 +2641,16 @@ dependencies = [
  "zerovec",
 ]
 
+[[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 = "1.9.0"
@@ -2603,6 +2824,61 @@ dependencies = [
  "wit-bindgen-rt",
 ]
 
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.114"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6532f9a5c1ece3798cb1c2cfdba640b9b3ba884f5db45973a6f442510a87d38e"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+ "rustversion",
+ "wasm-bindgen-macro",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.114"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "18a2d50fcf105fb33bb15f00e7a77b772945a2ee45dcf454961fd843e74c18e6"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.114"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "03ce4caeaac547cdf713d280eda22a730824dd11e6b8c3ca9e42247b25c631e3"
+dependencies = [
+ "bumpalo",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.114"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75a326b8c223ee17883a4251907455a2431acc2791c98c26279376490c378c16"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "web-sys"
+version = "0.3.91"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "854ba17bb104abfb26ba36da9729addc7ce7f06f5c0f90f3c391f8461cca21f9"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
@@ -2843,6 +3119,26 @@ dependencies = [
  "synstructure",
 ]
 
+[[package]]
+name = "zerocopy"
+version = "0.8.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2578b716f8a7a858b7f02d5bd870c14bf4ddbbcf3a4c05414ba6503640505e3"
+dependencies = [
+ "zerocopy-derive",
+]
+
+[[package]]
+name = "zerocopy-derive"
+version = "0.8.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e6cc098ea4d3bd6246687de65af3f920c430e236bee1e3bf2e441463f08a02f"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "zerofrom"
 version = "0.1.6"
diff --git a/Cargo.toml b/Cargo.toml
index df35e5b..7919ba5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -100,6 +100,7 @@ figment = { version = "0.10.19", default-features = false, features = [
 ] }
 tempfile = "3.14.0"
 serde_json = "1.0.140"
+criterion = "0.8.2"
 
 [lints.rust]
 # Deny unsafe code unless explicitly allowed
@@ -135,3 +136,6 @@ module_name_repetitions = "allow"
 # Allow some pedantic lints that can be overly strict for CLI tools
 too_many_lines = "allow"
 
+[[bench]]
+name = "benchmark"
+harness = false
diff --git a/benches/benchmark.rs b/benches/benchmark.rs
new file mode 100644
index 0000000..25e794e
--- /dev/null
+++ b/benches/benchmark.rs
@@ -0,0 +1,79 @@
+use criterion::{Criterion, criterion_group, criterion_main};
+use std::hint::black_box;
+
+fn line_key_old<'a>(line: &str, known_keys: &[&'a str]) -> Option<&'a str> {
+    let trimmed = line.trim();
+    if trimmed.is_empty() || trimmed.starts_with('#') {
+        return None;
+    }
+    for key in known_keys {
+        if trimmed.starts_with(&format!("{key} =")) || trimmed.starts_with(&format!("{key}=")) {
+            return Some(key);
+        }
+    }
+    None
+}
+
+fn line_key_new<'a>(line: &str, known_keys: &[&'a str]) -> Option<&'a str> {
+    let trimmed = line.trim();
+    if trimmed.is_empty() || trimmed.starts_with('#') {
+        return None;
+    }
+    for key in known_keys {
+        if trimmed.starts_with(key) {
+            let rest = &trimmed[key.len()..];
+            if rest.starts_with('=') || rest.starts_with(" =") {
+                return Some(key);
+            }
+        }
+    }
+    None
+}
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    let keys = vec![
+        "path",
+        "url",
+        "branch",
+        "ignore",
+        "fetch",
+        "update",
+        "active",
+        "shallow",
+        "sparse_paths",
+    ];
+    let lines = vec![
+        "path = foo",
+        "url=bar",
+        "branch = baz",
+        "ignore=qux",
+        "fetch = quux",
+        "update=corge",
+        "active = grault",
+        "shallow=garply",
+        "sparse_paths = waldo",
+        "unknown = fred",
+        "# comment",
+        "",
+        "  path = spaced  ",
+    ];
+
+    c.bench_function("line_key_old", |b| {
+        b.iter(|| {
+            for line in &lines {
+                black_box(line_key_old(black_box(line), black_box(&keys)));
+            }
+        })
+    });
+
+    c.bench_function("line_key_new", |b| {
+        b.iter(|| {
+            for line in &lines {
+                black_box(line_key_new(black_box(line), black_box(&keys)));
+            }
+        })
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);
diff --git a/src/git_manager.rs b/src/git_manager.rs
index ef3c9c8..8a1e485 100644
--- a/src/git_manager.rs
+++ b/src/git_manager.rs
@@ -933,8 +933,11 @@ impl GitManager {
         }
         for key in known_keys {
             // Match "key =" or "key=" at start of trimmed line
-            if trimmed.starts_with(&format!("{key} =")) || trimmed.starts_with(&format!("{key}=")) {
-                return Some(key);
+            if trimmed.starts_with(key) {
+                let rest = &trimmed[key.len()..];
+                if rest.starts_with('=') || rest.starts_with(" =") {
+                    return Some(key);
+                }
             }
         }
         None
diff --git a/src/git_ops/simple_gix.rs b/src/git_ops/simple_gix.rs
index 7679ab4..95bf3bb 100644
--- a/src/git_ops/simple_gix.rs
+++ b/src/git_ops/simple_gix.rs
@@ -111,4 +111,3 @@ pub fn fetch_repo(repo: gix::Repository, remote: Option<String>, shallow: bool)
         }
     })
 }
-