2019 Imac 27" Do I need an i7 or i9? I bought a 6 core i5 to replace my mid 2011 i5 4 core machine.

Something is amiss. Benchmark tests don't tell the full story but your new computer benchmarks almost twice as fast. EtreCheck is a diagnostic program written by an ASC member that lets us look under the hood of your computer without seeing any personal information. It would be a good idea to run it and paste the results here. We might find something that is eluding you.

One thing that immediately comes to mind though is this: lots has changed between 2011 and now. If you've not been updating software it could be that you are using programs that can't take full advantage of the OS, CPU, or GPU.

While your computer meets the minimum requirements to install Photoshop and for it to run, it is not any where near the specs required for optimum performance. The performance level you’re looking for requires at least 16GB of RAM, preferably 32GB. A large Raw file with several layers will slow down with only 16GB of RAM.

If you’re running dual monitors, 8GB of Video/GRaphis RAM is recommended. A single monitor will do fine with only 4GB of Video/Graphics RAM.

Many of processes will work with multi-core/multi-threaded processors, but Adobe recommends i7 and i9 processors for optimum performance. However, some of the filters etc. do not use multi cores/threads and in that case the single core with the fastest speed will perform the best. Recommended for best performance would be processors rated at 4Ghz or higher.

I’ve been a beta tester for Adobe for several years and have taught PS and LR for many years. My observations are based on requirements posted on Adobe’s site and personal experience with their products on multiple platforms etc. I hope this helps.

Run etrecheck again wilst doing Photoshop work & post a report so we can see better the weak points.

Hmmm, very curious...

Open Activity Monitor, sort on CPU%, see if anything using too much CPU% that isn't listed in etrecheck.

Sorry, if it seemed confusing. I was typing this at the same time you were posting with your system specs and I did not have a chance to review them.

I think there are two things holding you back with the performance you’re looking for in my opinion. Your choice of an i5 processor over an i7 or i9 is an issue. I think 16GB of Ram is limiting. My personal experience is I noticed a speed increase when going from 24GB to 64Gb of RAM. I think the sweet spot is 32GB or more.

There are several iMacs with speeds at 4Ghz and above. My 2017 iMac with 64Gb of RAM and an i7 processor at 4Ghz has none of your issues. I also use an older mid-2010 iMac as a second monitor. The single core processor speed can be less 4Ghz, but when the boost is applied to the single core it will exceed the recommended 4Ghz for single core performance. But any single core performance of 4Ghz (or higher) including boost, will speed up those filters etc. that perform best with high processor speeds.

The multi-core speeds do not need to be above 4Ghz and with many operations (but not all) more cores are better for faster performance. So, the 2017 iMac Pro and 2019 i7 and i9 iMacs can do quite well.

I have an iMac18,3 with the following specs:

That was the fastest processor at the time.

In running the smudge tool on a 582 MB photoshop file with Photoshop Elements 2020 the process takes forever to complete. The app was reported in Activity Monitor at taking nearly 300% of the CPU.

Here is how long it took to blur a face:

About 49 seconds. The image is 9600 x 15282. So you can try to get a feel for what that processor can do vs what you have. And don't know how big your image files are.

Off the subject: is your user name in any way referring to Corvettes?

I think Jeff has you covered nicely. :)

Maybe you have, but are you sure you have enabled GPU processing

in Photoshop preferences?