I just scrubbed a reply that was very similar to what you’ve said.
I am using an “old” CyberPowerPC that I purchased in August 2013 and this current version of MSFS runs way better than ANY of the previous versions I’ve owned–and that includes an X-Plane version or two.
Granted, I’ve upgraded the GPU (but it’s still only a Geforce GTX 1080) and maxed out the system RAM to 32 GB, but this program runs nearly perfectly on this old dog. Oh, I’ve had my issues with it and it took me a week to sort some of the things out, but all is well these days.
And I’ve “wowed” a couple of old FS users with the splendid eye-candy in this program. They can’t believe it!
I’ll close and say only that I’m looking forward to a few years of NOT having to add weather, clouds, fancy add-on aircraft, tons of expensive scenery and such. That in itself is a selling point for me. Sure, I can purchase a frames-per-second-killing add-on airport, but I don’t need to. Most of the stuff out of the box looks simply stunning.