Fix

Microsoft released a Windows Update Client Update which is part of the July 2016 Update Rollup to fix the long hang at Windows Update scan.

This update contains some improvements to Windows Update Client in Windows 7 Service Pack 1 (SP1). This includes the following:

• An optimization that addresses long scan time for updates that's reported on some computers.

1. Download:
   
   • 32 Bit
   • 64 Bit
2. Stop Windows Update service. This speeds up the setup of MSU updates. This can be done from the command line, or from the service manager window.
3. Try the downloaded update and see if it speeds up the installation of Updates.

To be able to install the update you first need to install the April 2015 servicing stack update for Windows 7 and Windows Server 2008 R2 update (again, stop WU service before trying to install the MSU).
Download (April 2015 servicing stack update):
32 Bit
64 Bit

Workaround 1

If this is still not helping to search for new updates, use WSUSOffline to get all the updates.