my_hash = {"a" => 1, "b" => 2, "c" => 3}
100_000.times { |i| puts my_hash["a"] }

my_hash = {a: 1, b: 2, c: 3}
100_000.times { |i| puts my_hash[:a] }

require 'benchmark'

string_AZ = Hash[("a".."z").to_a.zip((1..26).to_a)]
symbol_AZ = Hash[(:a..:z).to_a.zip((1..26).to_a)]

string_time = Benchmark.realtime do
  100_000.times { string_AZ["r"] }
end

symbol_time = Benchmark.realtime do
  100_000.times { symbol_AZ[:r] }
end

puts "String time: #{string_time} seconds."
puts "Symbol time: #{symbol_time} seconds."

String time: 0.1254125550040044 seconds.
Symbol time: 0.07360960397636518 seconds.