Use Serde's with attribute to shorten length encodings in Transaction

sdk/benches/short_vec.rs

@@ -0,0 +1,36 @@
+#![feature(test)]
+
+extern crate test;
+use bincode::deserialize;
+use solana_sdk::short_vec::ShortVec;
+use test::Bencher;
+
+// Return a ShortVec with 127 bytes
+fn create_encoded_short_vec() -> Vec<u8> {
+    let mut bytes = vec![127];
+    bytes.extend_from_slice(&vec![0u8; 127]);
+    bytes
+}
+
+// Return a Vec with 127 bytes
+fn create_encoded_vec() -> Vec<u8> {
+    let mut bytes = vec![127, 0, 0, 0, 0, 0, 0, 0];
+    bytes.extend_from_slice(&vec![0u8; 127]);
+    bytes
+}
+
+#[bench]
+fn bench_short_vec(b: &mut Bencher) {
+    b.iter(|| {
+        let bytes = test::black_box(create_encoded_short_vec());
+        deserialize::<ShortVec<u8>>(&bytes).unwrap();
+    });
+}
+
+#[bench]
+fn bench_vec(b: &mut Bencher) {
+    b.iter(|| {
+        let bytes = test::black_box(create_encoded_vec());
+        deserialize::<Vec<u8>>(&bytes).unwrap();
+    });
+}