I’m up to date with OS 10.13.3. Since 10.12+ I’ve been bothered by the beach ball intermittently appearing when internet pages load and slow startup of Word, Excel and Safari. My ram always seems to have at least 3 gig available.
½ of my hard disk is empty so a full disk is not the issue.
“Quick look satellite” frequently takes up 90% of my CPU when things are loading closely followed by Activity Monitor at 6 to 9%.
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Dave Gustafson
Well, first I wouldn't expect too much. You are talking about an 8-year-old Mac that was one of the slowest of the line even when it came out 8 years ago. Mac minis not only have budget processors, but also budget GPU (graphics chips). 8GB of RAM is only one thing, the GPU memory is important too. If performance is what you want, then expecting it out of a Mac mini is like expecting it out of a low-priced economy car.
Word and Excel are very pro-level apps that can be pretty demanding. One thing you may want to try if you really want to stick it out with your old mini is to try using lightweight apps like Numbers, Pages and even TextEdit when you can. TextEdit will be a lot less demanding on your CPU and GPU than Word. If you just need to write some text or view a document for reading, try TextEdit. It can even open many Word documents.
As for "QuickLook Satellite," that is what will show you a preview of whatever you have selected in the Finder. It can take up a lot of processor power when you have a large graphic or video selected. Do you have a lot of Finder windows open? Or a lot of tabs in a Finder window? If you are using Column View, maybe choose View, Hide Preview. I'd imagine that icon and especially Cover Flow view use Quicklook Satellite a lot, so you may want to avoid them. Maybe also if you have a cluttered desktop with lots of icons. I'd do everything I can to reduce the number of Finder windows, file icons, previews and other things that are visible or hidden behind other windows. And then, of course, a restart to make sure what QuickLook Satellite hasn't crashed or is stuck trying to render some video file or something.
Replace your hard drive with a ssd.
Do a Google search on "QuickLookSatellite MAC OS, High CPU Use" and follow the superuser.com results link. Among the several informative responses, the "Use qlmanage -r to reset Quick Look client's generator cache" seemed to fix the original poster's high CPU usage problem.