Optimize time range comparisons using step

time_range.rb

start1 = Time.parse('01:00')
end1 = Time.parse('10:00')
timespan1 = (start1.to_i..(end1.to_i - 1))
timespan1b = (start1.to_i..(end1.to_i - 1)).step(1.minute)

start2 = Time.parse('10:00')
end2 = Time.parse('18:30')
timespan2 = (start2.to_i..(end2.to_i - 1))
timespan2b = (start2.to_i..(end2.to_i - 1)).step(1.minute)

start3 = Time.parse('18:00')
end3 = Time.parse('23:45')
timespan3 = (start3.to_i..(end3.to_i - 1))
timespan3b = (start3.to_i..(end3.to_i - 1)).step(1.minute)

t1a = Time.now
resulta = !( timespan1.to_a & timespan2.to_a ).empty?
t2a = Time.now

t1c = Time.now
resultc = !( timespan1b.to_a & timespan2b.to_a ).empty?
t2c = Time.now

t1b = Time.now
resultb =  !( timespan2.to_a & timespan3.to_a ).empty?
t2b = Time.now

t1d = Time.now
resultd =  !( timespan2b.to_a & timespan3b.to_a ).empty?
t2d = Time.now

puts "#{resulta} #{sprintf "%.3f", (t2a - t1a) * 1000.0} ms - timespan1 & timespan2"
puts "#{resultc} #{sprintf "%.3f", (t2c - t1c) * 1000.0} ms - timespan1 & timespan2"
puts "#{resultb} #{sprintf "%.3f", (t2b - t1b) * 1000.0} ms - timespan2 & timespan3"
puts "#{resultd} #{sprintf "%.3f", (t2d - t1d) * 1000.0} ms - timespan2 & timespan3"