Windows 11 seems to reserve a lot of memory that isn't available to applications. The amount of in-use RAM on a freshly booted system is pretty high, and an 8GB system struggles under light load. I have one that can't run a VM on hyper-V, it just can't reserve even 512MB. The frustrating thing is that 6+ GB is in use but the applications visible in task manager add up to a small fraction of that, maybe 1-2 GB. I think it's being used mainly by the integrated graphics.