diff --git a/Cargo.toml b/Cargo.toml
index 76de893..2dee9d0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,11 +11,20 @@ categories = ["wasm", "no-std"]
 repository = "https://github.com/paritytech/wasm-instrument"
 include = ["src/**/*", "LICENSE-*", "README.md"]
 
+[[bench]]
+name = "benches"
+harness = false
+
+[profile.bench]
+lto = "fat"
+codegen-units = 1
+
 [dependencies]
 parity-wasm = { version = "0.42", default-features = false }
 
 [dev-dependencies]
 binaryen = "0.12"
+criterion = "0.3"
 diff = "0.1"
 rand = "0.8"
 wabt = "0.10"
diff --git a/benches/benches.rs b/benches/benches.rs
new file mode 100644
index 0000000..be87e7d
--- /dev/null
+++ b/benches/benches.rs
@@ -0,0 +1,51 @@
+use criterion::{
+	criterion_group, criterion_main, measurement::Measurement, BenchmarkGroup, Criterion,
+	Throughput,
+};
+use std::{
+	fs::{read, read_dir},
+	path::PathBuf,
+};
+use wasm_instrument::{
+	gas_metering, inject_stack_limiter,
+	parity_wasm::{deserialize_buffer, elements::Module},
+};
+
+fn fixture_dir() -> PathBuf {
+	let mut path = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+	path.push("benches");
+	path.push("fixtures");
+	path
+}
+
+fn any_fixture<F, M>(group: &mut BenchmarkGroup<M>, f: F)
+where
+	F: Fn(Module),
+	M: Measurement,
+{
+	for entry in read_dir(fixture_dir()).unwrap() {
+		let entry = entry.unwrap();
+		let bytes = read(&entry.path()).unwrap();
+		group.throughput(Throughput::Bytes(bytes.len().try_into().unwrap()));
+		group.bench_function(entry.file_name().to_str().unwrap(), |bench| {
+			bench.iter(|| f(deserialize_buffer(&bytes).unwrap()))
+		});
+	}
+}
+
+pub fn gas_metering(c: &mut Criterion) {
+	let mut group = c.benchmark_group("Gas Metering");
+	any_fixture(&mut group, |module| {
+		gas_metering::inject(module, &gas_metering::ConstantCostRules::default(), "env").unwrap();
+	});
+}
+
+pub fn stack_height_limiter(c: &mut Criterion) {
+	let mut group = c.benchmark_group("Stack Height Limiter");
+	any_fixture(&mut group, |module| {
+		inject_stack_limiter(module, 128).unwrap();
+	});
+}
+
+criterion_group!(benches, gas_metering, stack_height_limiter);
+criterion_main!(benches);
diff --git a/benches/fixtures/contract_terminate.wasm b/benches/fixtures/contract_terminate.wasm
new file mode 100644
index 0000000..00ca3c7
Binary files /dev/null and b/benches/fixtures/contract_terminate.wasm differ
diff --git a/benches/fixtures/contract_transfer.wasm b/benches/fixtures/contract_transfer.wasm
new file mode 100644
index 0000000..b0069f0
Binary files /dev/null and b/benches/fixtures/contract_transfer.wasm differ
diff --git a/benches/fixtures/dns.wasm b/benches/fixtures/dns.wasm
new file mode 100644
index 0000000..6825b88
Binary files /dev/null and b/benches/fixtures/dns.wasm differ
diff --git a/benches/fixtures/erc1155.wasm b/benches/fixtures/erc1155.wasm
new file mode 100644
index 0000000..0fd8ebb
Binary files /dev/null and b/benches/fixtures/erc1155.wasm differ
diff --git a/benches/fixtures/erc20.wasm b/benches/fixtures/erc20.wasm
new file mode 100644
index 0000000..7e561c4
Binary files /dev/null and b/benches/fixtures/erc20.wasm differ
diff --git a/benches/fixtures/erc721.wasm b/benches/fixtures/erc721.wasm
new file mode 100644
index 0000000..96ad573
Binary files /dev/null and b/benches/fixtures/erc721.wasm differ
diff --git a/benches/fixtures/many_blocks.wasm b/benches/fixtures/many_blocks.wasm
new file mode 100644
index 0000000..0f15be0
Binary files /dev/null and b/benches/fixtures/many_blocks.wasm differ
diff --git a/benches/fixtures/multisig.wasm b/benches/fixtures/multisig.wasm
new file mode 100644
index 0000000..bd7a96a
Binary files /dev/null and b/benches/fixtures/multisig.wasm differ
diff --git a/benches/fixtures/proxy.wasm b/benches/fixtures/proxy.wasm
new file mode 100644
index 0000000..01cd027
Binary files /dev/null and b/benches/fixtures/proxy.wasm differ
diff --git a/benches/fixtures/rand_extension.wasm b/benches/fixtures/rand_extension.wasm
new file mode 100644
index 0000000..c4a6710
Binary files /dev/null and b/benches/fixtures/rand_extension.wasm differ
diff --git a/benches/fixtures/trait_erc20.wasm b/benches/fixtures/trait_erc20.wasm
new file mode 100644
index 0000000..8b5b844
Binary files /dev/null and b/benches/fixtures/trait_erc20.wasm differ
diff --git a/src/stack_limiter/mod.rs b/src/stack_limiter/mod.rs
index 2e54bfb..02e2a3d 100644
--- a/src/stack_limiter/mod.rs
+++ b/src/stack_limiter/mod.rs
@@ -286,7 +286,7 @@ fn instrument_function(ctx: &mut Context, func: &mut Instructions) -> Result<(),
 					ctx.stack_height_global_idx(),
 					ctx.stack_limit()
 				);
-				new_instrs.extend(new_seq);
+				new_instrs.extend_from_slice(&new_seq);
 				true
 			} else {
 				false
diff --git a/src/stack_limiter/thunk.rs b/src/stack_limiter/thunk.rs
index 18eb150..d28cd35 100644
--- a/src/stack_limiter/thunk.rs
+++ b/src/stack_limiter/thunk.rs
@@ -82,7 +82,7 @@ pub fn generate_thunks(
 		for (arg_idx, _) in thunk.signature.params().iter().enumerate() {
 			thunk_body.push(elements::Instruction::GetLocal(arg_idx as u32));
 		}
-		thunk_body.extend(instrumented_call.iter().cloned());
+		thunk_body.extend_from_slice(&instrumented_call);
 		thunk_body.push(elements::Instruction::End);
 
 		// TODO: Don't generate a signature, but find an existing one.