Performance Issues for Just One User?

Hi Everyone,  

I have one user that has reported a variety of issues in Salesforce starting Monday of this week. We're in a large org and only this one user appears to be experiencing these issues. I'd consider the user to be a super user so they are very familiar with how things should function.  

• Various components on the page are loading at different speeds - doesn't seem to be object and/or record type specific and it could be in the layout, quick actions, the Activity feed, etc. 
• Search isn't working for lookup fields. 
• The Save button isn't available on some records when they are open to edit - and if the Save button isn't available, the user then gets a popup asking if they want to save changes when they leave the page. This is very random, they can open 3 records of the same type and 2 will have the Save button while the 3rd doesn't

What We've Tried:

• Happens in both Chrome and Edge (but Chrome seems worse) - we've confirmed we both have the same version of Chrome.
• It doesn't appear to be wifi related - they're not having issues with other apps or tools.
• They've restarted their router.
• They've restarted their computer multiple times. 

Any idea what's causing this, or better yet, how to solve it? 

Thanks!