mac os how to interpret memory and laptop tiredness

In addition to all the great things D.I. Johnson said, 8GB of memory just isn't a lot. A couple of years ago, I bought an MBA with 8GB because I needed a computer in a hurry, and it was what was available. I traded it in less than a year later. I had to spend too much time thinking about memory.

Some suggestions:

• Get rid of Chrome. It's a memory hog.
• Keep the number of programs running at a time to a minimum.
• Don't keep dozens of browser tabs and windows open.
• In Activity Monitor, what you want to keep an eye on is Memory Pressure. It's one of the graphs at the bottom. If it goes red, close apps. If that doesn't work, restart the computer.
• Restart regularly.

ihavques wrote:

[A]ctivity monitor… says my physically memory is 8.00 gb and only using 5-6.30 ish gb and cached files 1.90 ish gb and swap is 322.8mb (but they change around)

Cached Files is the amount of free RAM that is temporarily being used for holding cached files. Completely idle RAM does nothing for you, so macOS will often put free RAM to use holding cached files. If the Mac needs the cached data before it needs the RAM, that saves a slow trip to a drive. If the Mac needs the RAM first, it dumps cached data. "Cleaning" Cached Files to "recover RAM" is not needed and would defeat the potential speedup from putting free RAM to work.

Swap Used is the amount of storage space used on the startup drive to slowly simulate additional RAM.

You want Memory Pressure to be Green and Swap Used to stay relatively low.

There are any number of legit reasons why your Mac might be 'stressing' during use. RAM hungy apps, apps that are eating CPU cycles, system or application processes that have run errant.

You're on the right track to finding out what's going on by using Activity Monitor. In particular, look at the Memory Pressure reporting and the %CPU info. I find it helpful to use the column headings to sort %CPU in descending order when looking for whatever is eating those cycles.

This is Apple's guidance for using Activity Monitor: Activity Monitor User Guide for Mac - Apple Support

If, after you have taken a close look at what that app reports, you still cannot suss out the issue, then you might consider using another particular utility that is very popular here in the community for troubleshooting, EtreCheck.

Please run an EtreCheck evaluation of your Mac and post the generated report back here in a reply. EtreCheck is a safe and highly regarded utility from a trusted developer and respected ASC contributor. The report it generates will not include any personal info. It simply gathers specifics about hardware performance and installed software that might be in conflict with the OS.

Please navigate to EtreCheck.com to download the utility. Be sure to Allow Full Disk Access when you install the app. Once you’ve run the app and created your report please post it with your reply to this message. 

Please note you must upload the full report. To see how, please click >  How to use Add Text when posting… EtreCheck Report.

We’ll use your EtreCheck report to look for the things that may be causing your problem and advise how to correct them, all without having to play '20 Questions' back and forth here in the community.

Follow up -

By far one of the easiest ways to stress your Mac is to install junk like anti-virus, cleaning/optimizing, VPN or security applications. These are all junk apps, and the first rule of using a Mac is: Don't install junk. The Mac doesn't need these. They do nothing that macOS cannot do for itself.

Also, if you have trouble with reading the Activity Monitor app results yourself, post a screenshot or two here and someone will be happy to help.