Benchmark time lost in Ruby because of calls

ruby_calls.rb

$x = 0

def foo1
  foo2
end

def foo2
  foo3
end

def foo3
  foo4
end

def foo4
  foo5
end

def foo5
  foo6
end

def foo6
  foo7
end

def foo7
  $x += 1
end

$x = 0
time = Time.now
10_000_000.times { foo1 }
puts "foo1: #{Time.now - time}"

$x = 0
time = Time.now
10_000_000.times { foo2 }
puts "foo2: #{Time.now - time}"

$x = 0
time = Time.now
10_000_000.times { foo3 }
puts "foo3: #{Time.now - time}"

$x = 0
time = Time.now
10_000_000.times { foo4 }
puts "foo4: #{Time.now - time}"

$x = 0
time = Time.now
10_000_000.times { foo5 }
puts "foo5: #{Time.now - time}"

time = Time.now
10_000_000.times { foo6 }
puts "foo6: #{Time.now - time}"

$x = 0
time = Time.now
10_000_000.times { foo7 }
puts "foo7: #{Time.now - time}"

$x = 0
time = Time.now
10_000_000.times do
  $x += 1
end
puts "direct: #{Time.now - time}"

# Ruby
# ----
# foo1: 2.652264
# foo2: 2.393971
# foo3: 2.113695
# foo4: 1.864027
# foo5: 1.599237
# foo6: 1.313431
# foo7: 0.837017
# direct: 0.561372

# Crystal
# -------
# foo1: 0.0893159
# foo2: 0.0781229
# foo3: 0.0636261
# foo4: 0.0531781
# foo5: 0.0419328
# foo6: 0.0332189
# foo7: 0.033031
# direct: 0.036957

# Crystal (compiled with --release)
# ---------------------------------
# foo1: 1.00136e-05
# foo2: 0
# foo3: 0
# foo4: 1.19209e-06
# foo5: 0
# foo6: 0
# foo7: 0
# direct: 0