So as a phd student I’ve learned the thing about reading research papers is that yes, it takes ages to read your first 2-3 major papers in a field, but after that, you’ve probably picked up a lot of the vocabulary and basic ideas, and you’ll be surprised at how little content many additional papers have once you’re actually steeped in the lingo.
Accept that you're going to be slow. Start with a paper you know will be worthwhile, something seminal in your field.
Get rid of all distractions, preferably by going to a different environment. Leave your phone at home or at the very least silence it and leave it in your bag. Print the paper out on dead trees, or otherwise display it on a medium that cannot display a web browser or other digital distractions.
Just start reading, deliberately reading every word. Underline or take notes in the margin if those might be your thing. When you get to something you don't understand, don't skip past it and figure you'll fill it in from context - read it again and make yourself figure out exactly what it means (exception: you can try figuring things out from context, but limit it to several sentences). You might have to look some things up to gain understanding, which un/fortunately today is via the web, but don't get distracted. If you're feeling overwhelmed you can take a break, but don't jump to another activity. Stick with it.
Eventually you will learn how to read dense things quicker, how to quickly figure out where something fits in a field, whether reading something in depth is worth it. But that will only come with experience.