Interestingly, some experts say that 8K resolution will be needed to more accurately simulate the CRT using shaders / filters.
And even a NES currently requires ~3 Ghz for near-100% cycle-accurate emulation in Windows 10.
Imagine that, needing 3 Ghz and 8K to properly simulate an NES.
More res is always better, but flatpanels will never simulate crts fully because of crt blooming, which is a dynamic tone/contrast situation which shifts across the screen space non linearly. A very bright scene completely desaturates CRT colors, and drops contrast, flattening the image, while darker scenes look extremely pure and inky.
Pixel persistence will also not quite match CRTs. Even if it looks correct in a static image, it can not do it while moving.
CRT's don't have pixel persistence as they don't have "pixels." The equivalent would be screen burn-in, which you wouldn't necessarily want to emulate.
Even among CRT fans, blooming is seen as a problem (usually present to some degree but sometimes made worse by issues in the high voltage power supply) and wouldn't be necessary to emulate to get a good CRT effect.
The only flaws-become-features I'd want to chase in CRT emulation are those that were either purposefully taken advantage of to enhance the look of older games (like color artifacting in composite images, or blur which was purposely taken into account for dithering) or those that inadvertently became ingrained in the look and feel of classic games (scanlines, mild convex screen curvature, aperture grill blurring.) Zero lag, high color accuracy and excellent black level contrast are good ideals to chase regardless of whether or not you're trying to emulate a CRT.
Crt pixel persistence refers to the rise and decay of the phosphor, not the phosphor wear. This is a matter of motion clarity.
What you're describing is a thing CRTs do, but it's not called "pixel persistence."
Truth be told, I had a little bit of trouble finding what it
is called, because I always assumed it was "ghosting", but after looking it up that's also a term which mostly refers to LCD pixel persistence. "Image persistence" also turned up mostly LCD phenomena.
From what I can find, the effect you're describing seems to mostly be referred to as "phosphor persistence", "phosphor decay", or just "persistence" or "decay" when specifically used in the context of CRTs... which makes sense, because it's the phosphor coating on the back of the screen that determines how long this effect occurs. Different CRTs have differing amounts of this persistence, with it usually being way more noticeable on monochrome sets. So really you have two entirely different things called "persistence" depending on the display technology.
And yeah, I know this is pedantic, but CRTs have no concept of pixels. Pixels are strictly in the domain of the video game system plugged into the TV, as far as the tube is concerned it's receiving a stream of analog data. Calling the effect "pixel persistence" could misinform somebody trying to learn how the displays work.
IMO, this effect doesn't really have to be replicated for color CRT emulation because it's not that noticeable, but one thing I didn't initially think of: on earlier titles (particularly vector games) on monochrome sets it can contribute significantly to the look and feel of the game. For example, the missiles are much easier to see when playing on an original Asteroids cabinet than on most emulated versions because of persistence, and it has the effect of looking like a smoke trail coming off the missile. In these cases, it should certainly be emulated.
