Threads like this sure do start arguments fast... but I'll try to clear a few things up.
1. Just because Witcher uses up to 5GB RAM does not mean PC users were not sold up the river, consoles have 8GB of memory to spare now remember so memory this gen shouldn't become a problem as even when you factor in memory requirements of the software on each console the software is very basic and stripped down so I doubt it requires more than 1GB or so of that 8GB memory.
2. Static mesh pop-in is without question awful, you can fix a lot of things in Witcher with XML and user.settings changes but CDPR are going to have to do something about static mesh loading distance thats hard coded most likely because of consoles, why else would CDPR hard code it other than for parity across platforms so console gamers don't bitch and moan? On a similar note I'm still waiting for my particle count and density options on the PC version, CDPR.
3. Again on a similar note, you can increase such things as the draw distance of trees and bushes quite considerably without it having much of a impact on FPS. The 3 things that really bog Witcher down are nvidia hairworks, grass draw distance, and some may see sharp FPS drops out on the water if water is set to "ultra" where just like with hairworks when water is set to ultra tessellation is set to 64x. Visually the water looks identical even when tessellation is manually edited all the way down to 8x, but for hairworks I'd say bare minimum tessellation level you want is 16x, with 32x looking nice, 64x is again overkill.
4. Finally (I don't think I've missed anything), Witcher is probably as well optimised as it can be... for consoles and parity. Developers \ PR, whoever it is, needs to get out of this ridiculous "one size fits all" mentality, the reality is things do not work that way. Fortunately with the steam refund thing now in play hopefully this is something that will encourage the death of this stupid mentality. Consoles are the weaker platforms, console gamers just have to learn to accept that. I say this as a owner of not only a PC but a PS4 as well so my opinion is very much a honest neutral one.