Add benchmark results

Author: prevter

README.md

@@ -89,6 +89,60 @@ Options:
   -t, --test <value>: Test argument
 ```
 
+## Benchmarks
+
+Some benchmarks comparing `slic` with other popular C++ command line parsers:
+
+- [**CLI11**](https://github.com/CLIUtils/CLI11) (v2.6.1)
+- [**cxxopts**](https://github.com/jarro2783/cxxopts) (v3.3.1)
+- [**argparse**](https://github.com/p-ranav/argparse) (v3.2)
+
+Benchmarks were run on an AMD Ryzen 7 7730U using Google Benchmark library in Release mode with `-O3` optimizations.
+
+### 1. Simple case
+
+`program -v --count 42 myfile.txt`
+
+| Library  | Time (ns) | CPU (ns) | Iterations |
+|----------|-----------|----------|------------|
+| slic     | 51.8      | 51.6     | 13126669   |
+| CLI11    | 5752      | 5749     | 117156     |
+| cxxopts  | 7951      | 7951     | 71121      |
+| argparse | 3531      | 3531     | 200750     |
+
+### 2. Medium case
+
+`program -v --count 42 --name test --level 3 --output out.txt input.txt`
+
+| Library  | Time (ns) | CPU (ns) | Iterations |
+|----------|-----------|----------|------------|
+| slic     | 135       | 135      | 5237956    |
+| CLI11    | 12998     | 12995    | 54427      |
+| cxxopts  | 15516     | 15510    | 43210      |
+| argparse | 6582      | 6577     | 114666     |
+
+### 3. Complex case
+
+`program -v --count 42 --name test --level 3 --output out.txt --debug --threads 8 --timeout 1000 --retry 3 input1.txt input2.txt`
+
+| Library  | Time (ns) | CPU (ns) | Iterations |
+|----------|-----------|----------|------------|
+| slic     | 412       | 412      | 2178409    |
+| CLI11    | 28640     | 28623    | 25571      |
+| cxxopts  | 36981     | 36940    | 22162      |
+| argparse | 11283     | 11278    | 59623      |
+
+### 4. Flags only
+
+`program -a -b -c -d -e -f -g -h`
+
+| Library  | Time (ns) | CPU (ns) | Iterations |
+|----------|-----------|----------|------------|
+| slic     | 358       | 358      | 2089557    |
+| CLI11    | 12266     | 12259    | 57548      |
+| cxxopts  | 17721     | 17711    | 55006      |
+| argparse | 5063      | 5061     | 135891     |
+
 ## License
 
 This project is licensed under the MIT License. See the [LICENSE](LICENSE) file for details.