RAM usage in Windows

Is task manager supposed to somewhat-accurately reflect actual RAM usage? Because it seems like the percentages just don't add up. It'll say my RAM usage is in the upper 90%, but looking at the numbers in that column it won't add up to half of what my system has installed.

Granted, this is on an older laptop with 8GB and I can't upgrade it. I'm not expecting it to be a gaming rig. But it bothers me that the numbers to add up. Is there some way to figure out where my RAM is going to? Performance Monitor doesn't seem to have much more to say, either.

I've had that problem with every modern OS I've ever used. With the complexity of caching, shared memory, virtual memory etc the totals never add up.

Linux and macOS are just the same.

It's so annoying. It essentially makes the information useless. I mean yeah, I can see that Chrome is taking up a bunch of memory (of course it is), but it's hard to get too mad at it for taking up 2GB when I know I have 8GB and the rest of the stuff seems to add up to another 1.5GB.

So what's the point of telling me I have 3.5GB of programs running, Microsoft? Just to give me a vague idea?

Most likely the rest of the "RAM usage" is in the page cache, keeping inactive stuff around in case it is needed again in the near future.

You really do want your RAM usage to be near 100%, as otherwise the hardware is being wasted.

The system is slowing to a crawl though.

That's only (indirectly) related to RAM usage. The PC being slow is down to (basically) three things: (1) lots of CPU usage; (2) things needing to be paged-in when they're needed; (3) programs blocking on synchronous I/O.

Only (2) is RAM-related. And, yes, you might be right that something's taking too much RAM and squeezing other programs (or itself) out, but you should check that assumption first.

All of these values are in Task Manager, as optional columns in the Details tab. However, you might find Process Explorer easier to read.

Or you can poke around in Performance Monitor. It's been a while since I've had to look into any of this stuff, so I don't remember exactly which metrics you need to be looking at.