HP EliteBook 820 G3 Notebook and Photoshop

I would stay away from anything that has an Intel graphics card. They have the most issues with Photoshop, even when they meet the specs. Also avoid switchable cards and integrated cards. Get a computer when you can replace your own card, if you have to.

Machine needs to meet requirements and IMO large high resolution displays are best for editing images. CC version of Photoshop will scale its UI on high resolution displays. Photoshop is a resource hungry application and will perform better on powerful machines.  Photoshop is not that compute intensive but some features benefit from compute power.  You do not need a super computer for Photoshop.

Hi

See here for the minimum system requirements. Note though that these are minimum just to get the application to run

https://helpx.adobe.com/uk/photoshop/system-requirements.html

Dave