Add benchmarks to the README.md

I myself was astonished by the difference between rdo
and doas, so I felt like including it in the README.

README.md

@@ -44,3 +44,39 @@ session_ttl=5
 
 ### Dependencies
 - `libbsd`
+
+### Benchmarks
+
+The benchmark: Execute `whoami` 1000 times.
+
+|Program|Time|
+--- | --- 
+sudo | 13.62s
+opendoas | 7.60s
+rdo | 2.25s
+Baseline | 1.43s
+
+Baseline here is how long it took without any wrapper to make it root.
+
+These benchmarks were done on a single core of an `Intel i3-3110M` Laptop processor, on Artix Linux version `5.13.4-zen2-1-zen`.
+
+`sudo` and `opendoas` were pulled from the pacman repos, rdo via AUR.
+
+All configs were kept as default, except allow the `wheel` group on both + enable `persist` on doas.
+
+Script used:
+```sh
+#!/bin/sh
+
+$1 whoami
+
+current=$(date +%s.%N)
+for i in {1..1000}; do
+	$1 whoami 2>&1 >/dev/null
+done
+done=$(date +%s.%N)
+
+echo $done - $current | bc
+```
+
+The script requires `bc` to be installed, for floating point arithmetics.