Mudbox used to be relatively light and fast to use, don't know whether it's the same now and how viable it is for PBR texturing. 3dcoat has PBR painting features and an ability to create 'smart' material presets. I didn't seem as versatile as Substance Painter when I used it, but it wasn't too bad.
Back to answering OP question. I use to have a gtx 860 with i5 computer that ran Mudbox pretty well, It was the only solution I had for painting hi-res multi-tile textures, Because I couldn't run Mari properly, lots of display issues. Technically you can achieve PBR textures within Mudbox. Roughness maps is literally just…
The entire alien Covenant spaceship had barely any hand painted things on it. I setuped the mari archive allowing texturing it without any brush strokes. The only ones we did was to apply all the stickers and some specific dirt / stains on certain modules at the end of production. Most of the movie it's bare mari…