```ruby
str = "abc"

Benchmark.ips do |x|
  x.report("start_with?") { str.start_with?("a") }
  x.report("first ==")    { str.first == "a" }
end
```

```
Warming up --------------------------------------
         start_with?   282.381k i/100ms
            first ==   207.305k i/100ms
Calculating -------------------------------------
         start_with?     10.239M (± 2.2%) i/s -     51.393M in   5.022151s
            first ==      4.593M (± 4.5%) i/s -     23.011M in   5.021434s
```