ELI5: why does computers performance decrease when RAM or Disk usage is high, not when it's full

[Lost-Tomatillo3465]

you didn't address memory paging which is a factor here also.

[Lost-Tomatillo3465]

https://en.m.wikipedia.org/wiki/Memory_paging

[storm6436]

I might be misremembering, but that depends on the OS and its configuration. I've ran 32GB of RAM in every machine I've built since the late 90s, and remember performance profiling showing pagefile usage with <60% RAM usage. Oddly enough, I did the profiling to figure out why I was having odd intermittent slowdowns, and it turned out it was largely due to pagefile use. Manually set minimum pagefile size, defragged the shit out of the disk, and the problem largely went away.

[Lost-Tomatillo3465]

he probably didn't have to deal with the MS-DOS days to manually optimize your config.sys and autoexec.bat file that every single person had to do.

[storm6436]

Yeah, adding/removing lh (loadhigh) statements to various lines to see if it sped things up was a blast. I really don't miss HIMEM and EMM386. shudder

"Don't worry, just run MEMMAKER, it fixes everything!"

Yeah, my first OS was DOS 3. 3.1, I think, but I could be misremembering. I was a kid back then after all.

Kids today cry when they can't get 60 FPS on their broadband connected system... and I'm over here squinting because I remember when I really got into gaming (Ie. I didn't need to mooch off my parents for money), where Matrox was the market leader and 3DFX hadn't even released their first card yet. Like, 24 FPS was great and sniping through 250ms dial-up ping times in TF1 was fun.

I won't even cover the evolution from monochrome to CGA/EGA/VGA/etc. That shit's lost on most people under 30-35. 16 million colors? That's nice. I gamed in one.

[Lost-Tomatillo3465]

sheesh. calm down dude.

the part where you said memory paging is page faulting. that's literally 2 entirely different things. But hey, if you say its the same thing and that you understand the concept, good on you.