2011 MacBook slow on High Sierrq

macOS 10.13 High Sierra should work just fine on the laptop.

The most common issues for a slow Mac is a bad hard drive, some third party software interfering with the normal operation of macOS, or not enough memory or storage space, or a corrupt file system.

Run the Apple Diagnostics to see if any hardware issues are detected.

To look for possible software issues, memory & storage issues run EtreCheck and post the report here using the "Additional Text" icon which looks like a piece of paper. If you give EtreCheck "Full Disk Access", then the summary of the recent system logs will also be included which may provide some clues as well.

To check the health of the hard drive run DriveDx and post the report here using the "Additional Text" icon which looks like a piece of paper.

To check for file system issues run Disk Utility First Aid on the hidden Container. Within Disk Utility click "View" and select "Show All Devices" so that the hidden Container appears on the left pane of Disk Utility. Even if First Aid says everything is "Ok" click "Show Details" and manually scroll back through the report looking for any unfixed errors. If any unfixed errors are found, then you can try running First Aid while booted into Recovery Mode. If the errors cannot be fixed, then you will need to erase the whole physical drive and restore from a backup or clone.

If you have not restarted your laptop recently then do so now since macOS needs to be rebooted once in a while. Uncheck "Reopen windows" option before restarting macOS so that each open app will also have to relaunch fresh. Also disconnect all external devices in case one of them is causing a problem.

Hello oldkack,

Thanks for visiting Apple Support Communities. We understand that you're having some issues with slowness on your Mac running macOS High Sierra. See if the steps here help: If your Mac runs slowly

In addition to those steps, start your Mac to safe mode and sign in to your user account, then restart to exit safe mode. During the start up process to safe mode several steps happen that can help with performance like clearing of some system caches and such. More information on safe mode and how to start there can be found here: How to use safe mode on your Mac

Let us know how it goes.

Take care.

You should really identify the source of the problem before performing any upgrades as you may have multiple issues. Depending on how you use the laptop you may not need a memory upgrade. The EtreCheck report would give us an idea of memory usage especially if the laptop has not been rebooted in a while. If you have a software issue, then migrating, restoring from a backup or clone will just transfer the same software issues to the new SSD.

FYI, Apple does not upgrade drives in Macs. Apple will only replace the original hard drive with the same size drive which will be still be really slow and Apple's prices are extremely expensive for these components. This is a 10 year old laptop which no longer is supported by Apple nor is the laptop receiving any security updates to macOS. While I do like keeping older computers up & running you do need to weigh the costs & benefits. It may be worth upgrading to an SSD which can greatly increase system performance over even a healthy hard drive. An SSD can make sense since you can also later remove the SSD to use as an external drive if installed into an enclosure. I'm not sold on a memory upgrade (especially 16GBs) without seeing your current memory usage needs in the EtreCheck report. Software issues and a worn/failing drive are the most likely sources of the problem.