Have you tried running benchmarks that test various parts of the machine?
Yes, I have. A while ago… It’s been like that for a couple of years now.
I can only share with you my personal experience, as I don't claim expertise in technical matters. But I think I know what you mean by your problems with LRc, with delays switching modules, delays while selecting and switching from photo to photo, etc. It's very, very frustrating.
I agree that if the delay is "many seconds" it seems there is something very wrong with your current system.
Having said that, I've found with Windows, there are meaningful delays even with clean, well functioning laptops running well, and with desktops they still seem to lag Apple just a tiny bit (not enough to matter). Here is what I have experienced in your shoes:
My old 2019 laptop (same as your current 9th generation i9, but the laptop version, so that's slower, but with 32 gigs of ram, which is enough): It definitely "feels very slow", but not "many seconds" slow.
Changing modules, switching from GFX100RF photo to photo in the library, feels like 4-6 seconds when the system is running optimally (i.e., nothing else is open, nothing is happening in the background. LRc isn't doing something in the background like, I dunno, processing previews or something.
My new mid-tier "$900 MacBook Air" wannabe (AMD Ryzen AI 9). It "feels slow, but less so", maybe 3-4 seconds. Note, this is how it feels, I'm sure it's actually not that slow. But man it feels bad, especially when you're working with dozens of files.
The new top-tier $2.8K "creator" laptop (also AMD Ryzen AI 9, but more ram with better thermals and a discrete GPU which doesn't matter for the things we're talking about). It "feels okay". Disappointingly you can feel that it still takes 2 seconds or so - there's a delay which is really surprising. It's okay working with dozens of files, but it doesn't feel great since it's supposed to be "top of the line".
My new top-tier desktop (different AMD desktop 9 chip, 9950x). It "feels very fast" but sometimes there's as split second delay. Almost instantaneous but maybe a split second delay you can just kinda notice. Not a big deal but there.
MacBook Pro M4 Max. Everything feels snappy and instantaneous. Sometimes there might be a split second delay but it seems rare and not really noticeable, while on my desktop it seems to be there.
I don't know what to tell you. I think your desktop should be at least somewhere around where my new mid-tier laptop should be. Slow, sure, but "many seconds" sounds obviously wrong to me. But having said that, it might be time for a CPU upgrade given you're asking that chip to handle, I assume, your GFX100RF images. I've just noticed how those files blow up to gigabytes of data once you open them up to PS and start processing them with layers and the like, and the CPU chugs along at 100% while doing the simplest in LRc.