MacBook Air 7.1 (early 2015) freezes for five to ten minutes after login
This is going back to the basics.

Try a safe boot.
    Shutdown your machine.  Hold down the shift key.  Poweron.  The boot up will take longer than normal because the filesystem on the startup drive is being checked and repaired as needed.   All about safe mode including what features and apps safe boot leaves out.  Safe boot uses a software driver instead of using your machines video hardware.

  [http://support.apple.com/kb/ht1455][1]


Secondly, 

I'd run etrecheck. Your proprietary stuff gets filtered.

-- Download etrecheck.  The download link is at the bottom of the screen.
http://etrecheck.com/

-- Run etrecheck.   The first five runs are free.

-- How to install, run and report output for the EtreCheck Application
https://discussions.apple.com/docs/DOC-250000632

-- Explanation of EtreCheck  output by etresoft, the author
https://discussions.apple.com/docs/DOC-11591

How to report etrecheck data.

When the report is done, click on the export icon.

click on "Copy report" to copy to the clipboard

Get back in your web browser and access your discussion. Paste you etrecheck output into the code {} block.

which results in...

Robert