If you have a disconnected network drive or a poor network connection this could be the cause of Word loading slowly. As Word launches, it checks the available drives and if one is missing or the network connection is interrupted, it will hang. A good way of checking if this is the case is by opening Windows Explorer and seeing if this takes a little while to open.
Disconnected network drives can be disabled by removing them from My Computer – however this will only be a short-term solution and may cause you problems later on.
The best fix for this is enable caching, a function that makes Office remember where network drives are and avoid searching for them when launching Word and other applications in the suite.

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We can do this in the system registry. Go to
Start > Run, enter
regedit then click
OK.
In the Registry Editor browse to the relevant location depending on your version of Word:
For Office 2003:
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Common\Open Find
For Office 2007:
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Common\Open Find
Next, right-click in the right panel of the window and select New > DWORD Value.
Name the new value EnableShellDataCaching. Enter to confirm this, then right-click EnableShellDataCaching and select Modify on the menu.
Under Value data, type 1. Click OK to confirm, and exit the Registry Editor. Finally exit all programs and restart your PC.
When you next run Word, the problem should have resolved!