Q:

Editing XSD or XML Files in IntelliJ IDEA is Really Slow

I'm trying to edit an XSD file in IntelliJ IDEA but it's extremely slow to the point that it freezes for a couple of seconds after typing a character. The file is about 500 lines long so size shouldn't be the issue.
What is causing this and how can I fix it?
Note: I'm using IntelliJ IDEA Community Edition 2016.1.

A:

This is a known issue in IntelliJ: https://youtrack.jetbrains.com/issue/IDEA-24715
It occurs when editing an XSD/XML/properties file having the Structure View open. When editing the file, IntelliJ attempts to regenerate the structure on the fly, causing the freezes.

Solutions:

Update to the latest version of IntelliJ as the bug seems to be
fixed in newer versions. 
Failing solution 1, closing the Structure View will fix the issue:

Locate the Structure tab on the left hand side. It should look like the below.
Right click it -> Remove from Sidebar

