docs: Add benchmark

README.md

@@ -8,10 +8,12 @@ A tool I created to
 ## Usage
 ```
 Usage: b64 [-e] [-d] <string>
-
     -h, --help
             Display this help and exit.
 
+    -b, --benchmark
+            Benchmark b64
+
     -d, --decode
             Decode base64 to string.
 
@@ -47,6 +49,45 @@ encode this string to base64
 $
 ```
 
+### Benchmark
+```shell
+❯ zig build
+❯ ./zig-out/bin/b64 -b
+encode
+  280335 iterations     12401.51ns per iterations
+  40 bytes per iteration
+  worst: 138209ns       median: 10042ns stddev: 318640155486692400.00ns
+
+decode
+  282250 iterations     12048.95ns per iterations
+  28 bytes per iteration
+  worst: 76416ns        median: 10125ns stddev: 318604539142680300.00ns
+
+❯ zig build -Doptimize=ReleaseSafe
+❯ ./zig-out/bin/b64 -b
+encode
+  1284225 iterations    1228755.55ns per iterations
+  40 bytes per iteration
+  worst: 0ns    median: 416ns   stddev: 86582387.80ns
+
+decode
+  2295809 iterations    1226658.46ns per iterations
+  28 bytes per iteration
+  worst: 0ns    median: 375ns   stddev: 86582411.15ns
+
+❯ zig build -Doptimize=ReleaseFast
+❯ ./zig-out/bin/b64 -b
+encode
+  1355137 iterations    93007.39ns per iterations
+  40 bytes per iteration
+  worst: 526709ns       median: 83ns    stddev: 37608456664387784.00ns
+
+decode
+  2729217 iterations    105389.71ns per iterations
+  28 bytes per iteration
+  worst: 535583ns       median: 83ns    stddev: 36170163385699460.00ns
+```
+
 ## Build
 
 ```shell