add md5 bench

README.md

@@ -2,6 +2,41 @@
 
 Simple C lib of the MD5 & TEA algorithm
 
+# Performance
+Benchmark a `3.5MB` file comparing with `md5` command in `MacOS Mojave` by running three times `time` command then calculating their average.
+```bash
+# system command: total 22ms
+real    0m0.015s
+user    0m0.012s
+sys     0m0.005s
+
+# our md5 command: total 39ms
+# build by
+gcc md5.c -o md5 -O3 -DTEST_SIMPLE_CRYPTO
+
+real    0m0.021s
+user    0m0.013s
+sys     0m0.005s
+```
+Our version is `17ms` slower than what system does.
+
+Benchmark a `481.7MB` file comparing with `md5` command in `MacOS Mojave` by running three times `time` command then calculating their average.
+```bash
+# system command: total 2079ms
+real    0m0.980s
+user    0m0.964s
+sys     0m0.135s
+
+# our md5 command: total 2499ms
+# build by
+gcc md5.c -o md5 -O3 -DTEST_SIMPLE_CRYPTO
+
+real    0m1.253s
+user    0m1.003s
+sys     0m0.243s
+```
+Our version is `400ms` slower than what system does.
+
 # Install
 
 ```bash