Photographer using Macbook Pro SO incredibly slow/glitchy editing images

I see see enough problems here induced by people wiping Mac computers that I cannot make wipong my first recommendation in any circumstance.

Most slow Mac reports turn out to be caused by the useless third-party software just as Stumpy1946 cites. However, some external hard drives slow performance, so a quick first step is to test with no external drive attached to see if the symptoms persist. Same with external monitors.

Given we as your fellow end users can neither see nor touch your computer to diagnose it, the single best way for us to help in this forum setting is for you to post a system configuration report. Fortunately there is a safe, secure way to do that without our playing a protracted game of "20 Questions" that could go on for days.

We can quickly and within the confines of these forums help you determine what issues are at play if you use EtreCheck Pro, available here:

https://etrecheck.com/index

The free version will do nicely for this purpose, although the app is worthy of our financial support.

We can see hard data about drive performance, software interferences, and RAM usage. Etrecheck is the development of a long-serving and trusted contributor here expressly for displaying information in these forums to help us help you. It will not reveal any personal or secure information.

Please see this excellent user tip on posting long text reports like EtreCheck so th reprot does not get garbled.

How to use the Add Text Feature When Post… - Apple Community

At seven years old, your battery likely needs replacing. Apple recommends it be replaced when the remaining capacity gets to 80%. If yours won't hold a charge; replace it. You MBP is listed by Apple as "Vintage" and is one small step away from being obsolete.

The question is how much money, time and effort do you want to expend on a computer that will soon be obsolete?

Wiping and reinstalling the OS can make a computer faster IF you have an OS corruption issue or other problems a fresh OS might fix.

If you have any AV, helper app, optimizers, fixers or any other app that claims to make your computer faster, cleaner, better and etc, you need to uninstall all of them per the developer's instructions. ALL of them can cause system disruptions, "slowness" and the like.

I second the recommendations provided by Stumpy1946 and Allen Jones.

If you've decided that purchasing a new Mac might be the better option than fixing a Mac that can no longer be updated, then I'd offer the following:

You didn't mention anything about external monitors. If you use an external monitor, then either the MacBook Air M2 or the MacBook Pro would be a huge upgrade. If you use (or might want to use) more than one external monitor, then the mid or high "trim" level MacBook Pro would be the best option, as neither MacBook Airs or the entry level (M3) MacBook Pro will support more than one external monitor.

If you don't do any video editing, then I believe the MacBook Air (minimum 16GB) would be fine. If you do a lot of batch processing, then bumping the MBA RAM to 24GB or moving to the MacBook Pro would be advised.

I use an M2 15" MacBook Air with 16GB RAM and Photoshop/Lightroom work fine for me.