title: Building wheel for pandas on Ubuntu 20.04 takes more than 20 minutes, but not on 18.04
body: <p>I have an installation script for ERPNext that works just fine on Ubuntu 18.04.
  When I run the same script on 20.04 I am obliged to wait more than 20 minutes for it to complete where it takes around 30 secs on 18.04.</p>
  <p>My script includes these two lines:</p>
  <pre class="lang-sh prettyprint-override"><code>  ./env/bin/pip install numpy==1.18.5
    ./env/bin/pip install pandas==0.24.2
  </code></pre>
  <p>Their output is:</p>
  <pre class="lang-sh prettyprint-override"><code>Collecting numpy==1.18.5
    Downloading numpy-1.18.5-cp38-cp38-manylinux1_x86_64.whl (20.6 MB)
       |████████████████████████████████| 20.6 MB 138 kB/s 
  Installing collected packages: numpy
  Successfully installed numpy-1.18.5
  Collecting pandas==0.24.2
    Downloading pandas-0.24.2.tar.gz (11.8 MB)
       |████████████████████████████████| 11.8 MB 18.0 MB/s 
  Requirement already satisfied: python-dateutil&gt;=2.5.0 in ./env/lib/python3.8/site-packages (from pandas==0.24.2) (2.8.1)
  Requirement already satisfied: pytz&gt;=2011k in ./env/lib/python3.8/site-packages (from pandas==0.24.2) (2019.3)
  Requirement already satisfied: numpy&gt;=1.12.0 in ./env/lib/python3.8/site-packages (from pandas==0.24.2) (1.18.5)
  Requirement already satisfied: six&gt;=1.5 in ./env/lib/python3.8/site-packages (from python-dateutil&gt;=2.5.0-&gt;pandas==0.24.2) (1.13.0)
  Building wheels for collected packages: pandas
    Building wheel for pandas (setup.py) ... done
    Created wheel for pandas: filename=pandas-0.24.2-cp38-cp38-linux_x86_64.whl size=43655329 sha256=0067caf3a351f263bec1f4aaa3e11c5857d0434db7f56bec7135f3c3f16c8c2b
    Stored in directory: /home/erpdev/.cache/pip/wheels/3d/17/1e/85f3aefe44d39a0b4055971ba075fa082be49dcb831db4e4ae
  Successfully built pandas
  Installing collected packages: pandas
  Successfully installed pandas-0.24.2
  </code></pre>
  <p>The line &quot;Building wheel for pandas (setup.py) ... /&quot; is where the 20 min delay occurs.</p>
  <p>This is all run from within the Frappe/ERPnext command directory, which has an embedded copy of pip3, like this:</p>
  <pre class="lang-sh prettyprint-override"><code>erpdev@erpserver:~$ cd ~/frappe-bench/
  erpdev@erpserver:~/frappe-bench$ ./env/bin/pip --version
  pip 20.1.1 from /home/erpdev/frappe-bench/env/lib/python3.8/site-packages/pip (python 3.8)
  erpdev@erpserver:~/frappe-bench$ 
  </code></pre>
  <p>I would be most grateful for any suggestions how to speed it up.</p>