require 'benchmark'
require 'net/ssh'

count = 15
user = 'manu'
host = 'xx.xx.xxx.xxx'
port = '22'
password = 'pass'

Benchmark.bm do |bm|
  bm.report('Close session') do
    count.times do
      session = Net::SSH.start(host, user, password: password, port: port)
      session.exec!('hostname')
      session.close
    end
  end

  bm.report('Reuse session') do
    session = Net::SSH.start(host, user, password: password, port: port)
    count.times do
      session.exec!('hostname')
    end
    session.close
  end
end

###
#
#      user     system      total        real
# close session  1.890000   0.260000   2.150000 ( 27.267397)
# reuse session  0.140000   0.040000   0.180000 (  6.670353)