Why is the new Photos app so slow on my Mac?

Same here. Though I like some of the features of the new photos app, I am very displeased with its slow performance. It seems like I'm not able to edit in real time. I did not get to copy my old Iphoto Libraries into Photos, I don't have the ability to arrange photos or groups by folders or sub folders as previously in iPhoto, nor am I able to export them within the App and add my watermark on them. I will have to resort to using Lightroom. This is the reason why I avoided updating for so long. Really wish Apple would do better about this update remorse so many people are experiencing. This can't be good for the long run. It's as if I'm editing film, verses a photo.By the way I have a Quad Core processor with 16GB of Ram.

You do not understand Photos

I did not get to copy my old Iphoto Libraries into Photos

No copying involved but Photos will open and migrate iPhoto (and Aperture) libraries keeping the organization

I don't have the ability to arrange photos or groups by folders or sub folders as previously in iPhoto

Photo supports exactly the same album/folder structure that iPhoto did - no difference at all

nor am I able to export them within the App

I have no idea what this means

add my watermark on them.

Of course you can - many ways, easiest is to edit in Preview

You need to learn how to use Photos - when you do you will find that it is superior to iPhoto in nearly every way but it is a different program, does have a leaning curve and does require different work flows - but learning it is much, much easier than learning LightRoom which had a giant learning curve and requires all, totally new work flows

LN

"nor am I able to export them within the App and add my watermark on them" I am not able to export and add a watermark within the app as I could with iPhoto. I am a photographer doing large group exports at a time. I looked into your suggestion to use preview and it seems like I would have to export one photo at a time. This is really a problem for me. With iPhoto I could export 100's of photos at a time while adding my watermark. If you have a workflow that would help me, please send an example.

I am not able to export and add a watermark within the app as I could with iPhoto.

Actually you could never do that with iPhoto - there is a third party plugin that can do that in iPhoto and the third party does not supply that product for Photos - once again with photos you can edit with any external editor and preview can do watermarks as can many other editors

LN

Perhaps you should start a separate topic to get some proper answers to your question. I have never needed any batch watermarking feature myself, but I can understand you need this function.

A quick search at Macupdate.com gave me some tips: https://www.macupdate.com/find/mac/watermark%20jpg

Should you start a separate topic, you might want to ask whether anyone has experience (or can recommend) any of the listed apps, or perhaps others?

A quick search on "watermark photos" at Apple's AppStore also gave a number of suggestions.

Absolutely right! Although your iMac might be getting a little old, it can still run the 'latest and greatest' OS, and I see you are running High Sierra. According to MacTracker, your iMac can have up to 32GB RAM, although I assume that 16GB should be sufficient.

I'll never get accustomed to the fact that a Mac needs rebooting every few days. While I have still been using Linux on a PC or Unix on my Sun Sparc station, I felt bad, if I had to reboot my computer after only a month. An up-time of at least half a year was perfectly normal and expected. I only restarted the work station for some system upgrades. The daily, weekly, and monthly cleaning daemons worked very well automatically in the background to get rid of garbage and to clean the caches during the night. In the morning my computers were ship-shape.

I am in complete agreement with you provided the computer has sufficient resources to run for extended periods of time without digging itself into a hole. I would add to your list the OpenVMS servers I supported which could get by with annual reboots usually for other reasons then problem with them.

But in the case of a computer that is short of RAM, a work around until the RAM can be increased is to reboot it on a regular schedule. I do not see this a permanent solution just something to get you over the hump.

Thanks for all your help everyone!

I will try to increase the RAM and see if that helps.

Old Toad, I've been running "Photos" since my upgrade to High Sierra a few months ago. Before that, all my pics were in iPhoto on various Macs since the 1990s. So my Photos library is quite large, over 9,000 pics. ... I can't see anything called Adobe Switchboard ...

Thanks again.

Read this:

Updating from iPhoto to Photos for macOS - Apple Support

Download and run Etrecheck. Copy and paste the results into your reply. Etrecheck is a diagnostic tool that was developed by one of the most respected users here (and recommended by Apple Support personnel) in the ASC to help identify the more obvious culprits that can adversely affect a Mac's performance.

I have the same issue with the Photos app running super slow, I really dislike the Photos app, it takes a good 15-20 minutes to fully load the app, and I can't sync photos back to my iPhone, it sticks on "waiting for items to copy". Old iPhoto loads in about 30-60 seconds. All other apps on my late 2012 MacBook Pro Retina run just fine. Frustrating the new Photos app performs way worse than iPhoto. Apple's software has really dropped in quality over the last 2 years, they've released some of the buggiest software lately. I wish they'd take a little longer before releases to fix some of issues. I'm running the latest of everything and I sync via USB not over the air or iCloud Photos. And another thing, the 'Photos' app and 'Photos Agent' use significant energy and large amounts of CPU even when idle.

Read my previous post.

I have this exact same problem. Even with all the complaints about iPhoto and the big switch, i was much happier with the performance prior to the Photos app. Just getting the photos from my phone - USB to MBPr - takes so long i just close the app and cross my fingers for an update... been almost 20 min right now and i'm waiting on no more than 20 pics and 1 vid to appear and nothing but loading grey squares.

I am very disappointed with this new Photo app.