My MacBook Pro from 2013 isn't working well

👍

EtreCheck is perfectly ok despite its absence from the App Store. Follow these instructions: How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report - Apple Community. It will probably implicate the battery, but it will also include a comprehensive amount of other potentially contributing factors such as those HWTech alluded to.

In any event we have to fix hardware first. Macs and macOS demand perfectly functioning hardware.

We can discuss the reasons EtreCheck isn't in the App Store if you still don't trust it. You're wise to be circumspect regarding such things, but EtreCheck isn't something you install on a Mac. It alters nothing. It is merely downloaded and run, and you can get rid of it as easily as dragging its icon to the Trash if you so choose.

To address the performance issues, you need to run the third party app EtreCheck and post the complete report here so we can examine it for clues. The most common causes for poor performance are from using the following types of software since they interfere with the normal operation of macOS and are not needed at all (forum contributors will ask you to uninstall them if they appear in the EtreCheck report):

• Anti-virus apps
• Cleaning/optimizer apps
• Third party security software

From your description it's quite likely its battery needs to be replaced. A battery in need of replacement will result in poor performance.

Due to its age I doubt Apple will replace that battery any more, but if you contact them they might recommend another repair shop. Contact Apple, here: Official Apple Support

Apple doesn't have sales.

Etrecheck Used to be in the Mac App store, but the Mac App Store rules were tightened, precluding access to certain system calls that were completely non-invasive, but violated the App store rules for "average" Apps.

The developer decided he did not want to toss out important (for Etrecheck) functionality, just to stay in the Store, so he kept the features and pulled it outside the Mac App Store, hosting it on his developer web site, and allowing Free use at his own expense.

Free Download ONLY from:

http://etrecheck.com

The Mac is certainly old, and you may wish to take its age into account when deciding to replace its battery, but other problems are contributing to its poor performance.

Antivirus software: Apple, Webroot, and Malwarebytes

That entry should resemble exactly the following:

Antivirus software: Apple

... and nothing else.

Fix the battery too, but "Webroot" is garbage that has no place on a Mac. Rule 1 of Macs is don't install junk. If you decide to replace that Mac with a newer one, avoid repeating that all-too-common mistake.

The anti-virus software, especially WebRoot, is most likely the main source of the problem. It certainly does not help that you have dueling anti-virus products which makes things even worse because they will be stepping on each other's toes. Don't worry about the battery at this time, until you see how the system performs once you have uninstalled both of these items.

The report also shows the system using about 1.4GB of Swap which means you may not have enough memory for your workloads. Perhaps it is caused by the anti-virus software. 4GB of RAM is way too little these days.