Compare parsing an int as intermediate strings vs using a byte parser directly on the IO

bench_parse_int.cr

require "benchmark"

int = 0
[1, 12, 1234, 12345678, 1234567812345678].each do |number|
  puts "Parsing #{number}..."
  io = IO::Memory.new
  io << ":#{number}\r\n" # Redis integer format
  io.rewind

  Benchmark.ips do |x|
    x.report "to_i" do
      case byte = io.rewind.read_byte
      when ':'
        int = io.read_line.to_i64
      end
    end

    x.report "byte" do
      int = 0i64
      case byte = io.rewind.read_byte
      when ':'
        loop do
          case (next_byte = io.read_byte) 
          when '\r', '\n', nil
            break
          when '0'.ord..'9'.ord
            int *= 10
            int += next_byte - '0'.ord
          else
            break
          end
        end
      end
    end
  end
  puts
end
pp int

results.txt

Parsing 1...
to_i  29.71M ( 33.65ns) (± 0.51%)  16.0B/op   6.14× slower
byte 182.42M (  5.48ns) (± 1.06%)   0.0B/op        fastest

Parsing 12...
to_i  28.14M ( 35.54ns) (± 1.11%)  16.0B/op   4.56× slower
byte 128.41M (  7.79ns) (± 1.34%)   0.0B/op        fastest

Parsing 1234...
to_i  23.85M ( 41.93ns) (± 4.85%)  32.0B/op   3.38× slower
byte  80.68M ( 12.39ns) (± 1.12%)   0.0B/op        fastest

Parsing 12345678...
to_i  21.22M ( 47.12ns) (± 0.73%)  32.0B/op   2.14× slower
byte  45.47M ( 21.99ns) (± 3.65%)   0.0B/op        fastest

Parsing 1234567812345678...
to_i  17.98M ( 55.62ns) (± 0.44%)  32.0B/op   1.38× slower
byte  24.80M ( 40.32ns) (± 0.45%)   0.0B/op        fastest