"Character pop-in on Switch 2 is also typically a match for PS4. On long views, NPCs that are present on PS5 are absent from the weaker consoles. When we actually approach those NPCs, Switch 2 and PS4 usually pop in at about the same distance, though curiously in one test Switch 2 is delayed slightly. This is only really a factor in town areas, as other parts of the game are NPC-light."

In a game built for the much slower I/O speeds of the PS4, I find it highly unlilkely that data streaming would be a bottleneck on Switch 2.
NPC counts are typically a CPU issue, and given we know Switch 2 is only slight better than PS4 in the CPU department I would bet that's the limiting factor.

Could be memory bandwidth as well.

Either way, we have swayed from the original bump.

The bump was someone claiming drive speeds have a significant impact on game performance, that isn't true.  Drive speeds reduce loading and are faster at data transfer.  Very limited impact to actual game performance.  

A few PC games have optional ultra texture packs where drive speed can start having a marginal impact, but those packs aren't on consoles, certainly not the S2.

Side note, the drives I put in my rig are 12,400 mb/s.  I have tossed a 600 mb/s bulk storage drive as well.  I can play games from either drive.  Outside loading and Rift...  there is no difference.

Edit

The other point was the ps4 supports external at 600 mb/s which is faster than S2 game carts...

I still think a CPU bottleneck rather than bandwidth would be more likely when talking about NPC counts as the main demands there are skinning, animation, routines, etc. Same reason we see similar NPC and traffic density in Cyberpunk between Switch 2 and PS4 despite elements like data streaming, textures, etc being much better on Switch 2.

Yeah I'm no expert so I honestly have no idea whether faster I/O has any bearing on in-game performance, but I would theorise there's probably some degree of performance boost gained from the FDE, since it offloads decompression duties from the CPU.

My gut tells me the NPC density is bandwidth more than CPU.  The ps4 is 8 gb at 176 gb/s, while the S2 is 12 gb at 102 gb/s.  The bandwidth is just going to limit density, fps and resolution.  Luckily DLSS is an easy workaround for resolution.

I am far from an expert, and couldn't lay out details, my positions come from experience.  I have tried different GPUs, CPUs, Ram, overclocking, etc on my rig.  GPU changes immediately make massive impact.  CPU makes a solid impact.  Ram overclocking was marginal, the other stuff (like storage speeds) was negligible. 

Kind of arbitrary numbers but GPU feels like 60% of the game, while CPU is 30%, Ram is 9% and everything else is 1%.  I still maintain raw GPU power rules the day.  The difference between my old 4070 and 4090 (everything else was identical) was generational, despite both GPUs being the same "generation."  It is why I don't think time is a good benchmark for generation definitions, power is.  A 3090 outperforms a 5060ti, despite the 3090 being a 2020 GPU while the 5060ti is 2025.  Raw power is king at this point in time.  Perhaps AI will change that in the next few years. 

@Chrkeller

When it comes to NPCs, it's CPU first, then everything else.

Fair, I am happy to concede that point.  I am a chemist, not a computer pro, my views are mostly messing around on my PC.  And it makes sense.  The Series S has way lower bandwidth compared to the Series X, but same (ish?) CPU, and it has the same NPCs.  Fair, thanks for the clarification.

Out of curiosity, Hitman on the Switch 2 has lower resolution NPCs in the distance, memory bandwidth or still CPU?  

Not sure about Hitman issues on Switch 2 - are NPCs with lower quality assets in distance, or they're animating at lower frame rate (or both)? 

General rule of thumb with NPC crowd density is that it's CPU bound, due to logic and animations, then everything else follows.

I haven't played it, just read. DF article that said NPCs in the distance are lower resolution and as you approach they increase in resolution.

Haven't seen it, but my guess, if they appear to be lower resolution, that it's more aggressive LOD scaling and maybe variable rate shading. Hitman is packed with dense crowds, which are very taxing not only for CPU, but for every other subsystem as well.