Patch 7.1 added a lot of exciting content, but also added a problem for a lot of users. Upon going to Dalaran and certain other places, the loading screen would take forever to load, and there is luckily a solution to bypass this problem. After following this guide you will notice a very good improvement upon logging in, switching continents and loading Dalaran.
Here's how to do it:
Close WoW and open the Battle.net launcher. Click on "Options" and select "Game Settings". Click on the "Streaming" tab and turn off streaming there. After doing this, save the settings, and your loading times are much better! This will not affect any of the in-game features unless you plan on using the Battle.net launcher to stream to Twitch.
Blizzard offered an alternative solution to the problem in which you could delete your cache folder in the WoW installation folder, but most people don't get any better loading times by doing this.