Are you using PS and/or LR on a 15" laptop with 4k monitor?

Probably usable, but don't spend extra money on it. 4K makes sense on a 24 or 27 inch desktop monitor, but on a 15 inch screen it's well beyond what the eye can possibly resolve. You can't put your nose right up to the screen, there's a limit to how close you can get.

It's basically a marketing gimmick. Looks good on paper and probably sells a boatload of units, but without much practical relevance. The MacBook Pro 15 inch resolution of 2880 x 1440 (aka retina) is about the absolute limit of usefulness.

Hi

Not sure about Lightroom but there's a thread here for Photoshop

Photoshop support for 4k display

I can certainly remember threads from people who were doing exactly that.   The problem is that you ask a first time poster questions, and they often don't answer, so we don't get the feedback to pass on to people like yourself.  Personally, I think it risky.

You can set the Photoshop UI (user Interface) to 200% making it just about usable, you'd be stuffed with regard to most third party plugins.  In the last thread I worked out that a particular panel would be 3mm X 40mm linear size on the screen, and probably impossible to see.  

Hi Bazsl,

That shouldn't be happening as Photoshop and Lightroom are not scaling your fonts correctly, could you please let us know the version of Photoshop and operating system you're working on? Is the font size too small to read?

Also, please take a look at the below similar discussion and let us know if that helps:

4k monitor | Photoshop Family Customer Community

Too small UI on 4K display!

Thanks,

Akash