title: Why docker build is so slow
body: <p>My docker is very slow when I'm trying to build images on my laptop.
  I tried to build same image at my ubuntu inside virtual machine with same docker version and it builds it in 5 seconds, but on my laptop it evaluates every statement like 30 times slower. 
  Even <code>ENV</code> command!</p>
  
  <p>Laptop uses OpenSUSE 42.2 Leap with Btrfs as root file system, HDD with 5400 rpm and also it's encrypted.
  I know all these factors but are they so significant that my build takes 15mins instead of 5sec?</p>
  
  <p>Docker 1.13.1.</p>
  
  <p>Thanks.</p>
  
  <p><strong>UPD.</strong></p>
  
  <p>not sure if it helps or not, but when I run <code>docker build -t test .</code> on my virtual machine, it uses 10% of my 4-core CPU for 5 secs and heavilly uses HDD.</p>
  
  <p>however on laptop it uses one core of my 4-core CPU for 100% all the time and HDD remains idle almost all the time.</p>
  
  <p>here is nmon statistics:
  <a href="https://i.stack.imgur.com/ra6mZ.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/ra6mZ.jpg" alt="enter image description here"></a></p>