Photos app on my 2014 27 inch iMac has problems with my 3 terabytes of family photos. Suggest a replacement machine?

Your EtreCheck report indicates the computer has not been restarted in 26 days, a restart is certainly warranted. In addition, yes the computer is obsolete and is still using the original Fusion Drive. Your next computer should have SSD storage (I'd recommend up to 2 TB) which is considerably faster and more reliable than any computer that relies on a HD. Please remember a Fusion Drive is a small SSD and a traditional HD fused together with software, while faster than a traditional HD system there is still a HD and yours is 10 years old and could fail at any time!

My solution to this was to upgrade to a Mac that supports Thunderbolt 4 and to get an external drive that supports Thunderbolt 4. What I ended up with is an iMac with 2 TB of SSD storage and an OWC Thunderbay 4 which you can find at https://eshop.macsales.com/shop/thunderbay-4/thunderbolt-3-raid-5. I configured the Thunderbay 4 for RAID 4 to get some redundancy so if/when a drive dies (they all eventually do) I can easily swap it out and not lose any data. In addition to my 4.5 TB photos library I also store my video library on the Thunderbay 4 which is another 10 GB. You can also get a Thunderbay Mini and install SSD's in it which would be quick but expensive too. You can find those at https://eshop.macsales.com/shop/thunderbay-4-mini/thunderbolt-3

No, this is not a cheap solution but it works extremely well and has serviced me for about 3 years now.

To eliminate some possible contribution to slow performance the iMac's internal drive, what storage is inside?

To give the best description of the storage device, its specs and its speed, posting a system config report will help us better understand your iMac's capabilities. I can show if a slow internal storage is hindering the externals from working to best capacity.

Fortunately there is a safe, secure way to do that without our playing a protracted game of "20 Questions" or "Try This Next" 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 issues, 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.

For you issue, EtreCheck can also detect a known bottlenecking sub-process in Photos, photoanalysisd

This excellent user tip helps with posting long text reports like EtreCheck here.

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

RAID does not hinder the performance all it does is to ensure you have the uptime you need. You may want to consider a base model Mac Studio and a drive like I suggested or something like an OWC ThunderBlade

which would provided the fastest throughput out there right now. You would have a screamer for sure.

I don't see any of the usual suspects in the report. However, your read and write speeds are lower than expected:

Write speed: 255 MB/s

 Read speed: 716 MB

You could benefit from an external SSD that you've cloned your boot drive to and boot and run from it. I recommend drives from OWC (MacSales.com) as they have proven reliability, excellent customer support and warranties.  Consider one of these depending on your budget and needs: 

OWC Envoy Pro FX Thunderbolt 3 + USB-C Portable NVMe SSD**

OWC Envoy Pro SX Rugged Portable NVMe SSD with Thunderbolt/USB4

OWC Envoy Pro Elektron USB-C portable NVMe SSD

Envoy Pro EX with USB-C or USB 3 

For your particular Mac model contact OWC's customer support and get their recommendation for the SSD model that would best suit your iMac model, work requirements and budget.  They may have additional models other than those I've shown above.

Also you haven't rebooted in 26 days. That's way too long. Rebooting frequently will clean out temporary system and application cache and swap files. That will help with performance. I shutdown every night and reboot in the morning. However, every other day would be good practice.

Your first reboot should be a boot into Safe Mode according to How to use safe mode on your Mac and then a normal reboot.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

I wonder if the problem is really with the machine … or with the Photos app. It could be that if you have a very large library, you need to look at commercial applications that are designed with extremely large catalogs in mind.

There is one called Mylio.

https://mylio.com/

I don’t know much about it, or have any experience with it, other than seeing people occasionally mention it. But you could add it to a list of “things to research.”

As far as your current setup goes, putting the master copy of your Photos Library onto an external SSD might help. (I don’t know if it would help enough.). But I would strongly advise using HDDs for backups… SSDs left unpowered for long periods of time (years?) can lose data.

ku4hx wrote:

I think the first thing I'd to is move the photos to external storage.

Obviously if the photos are important to you, you'd need to back them up to an equally large backup drive.

The images ARE on an external drive. See the next to last line:

The macOS library that is used by the Photos app is 100% on the external drive.

I think the first thing I'd to is move the photos to external storage.

Obviously if the photos are important to you, you'd need to back them up to an equally large backup drive.