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Apps on iMac Slow to Start Up  



I'm looking for some suggestions here. I have an 2015 iMac 27" Retina 5k. It has 16GB of memory and a 1TB Fusion drive. SO I have plenty of horsepower.

The problem is at times I see some apps taking over a minute to start up. I can watch the icon bouncing in the dock for a long time before they start up. Apps such as Chrome, Word, Pages, etc.

I have tried looking at Activity Monitor while this is happening but I don't see anything causing this delay. There is plenty of free memory, plenty of storage, yet it can take quite a while for some things to start up. 

I've run the various things like Disk Utility, EtreCheck, Clean My Mac, and the likes.

I'm wondering if by chance the Fusion drive could be an issue. I've contemplated getting at external SSD to see if that makes a difference, but wanted to put the question out here first to see if there are other ideas that people have that I could try.

Any ideas from anyone? Thanks in advance.


What did EtreCheck say. It is a report intended to be shared unless you know exactly what you are looking for?


Have you tried booting into Safe mode?
This will not load any 3rd party additions, it will load some more conservative Apple drivers (may cause screen flicker), and it will clear some kernel caches (a cache is saved data in a form that can speed up a program, but is totally redundant to the original source, and thus can be safely cleared). Booting into Safe mode is just an experiment, but can frequently eliminate any 3rd party interference, or a cached item out-of-sync with the world. (Verify Safe mode via Applications -> Utilities -> System Information -> Software -> Boot Mode -> Safe vs Normal)


Yes, a Fusion drive could have issues with the rotating hard disk portion of the drive. While your iMac is not that old, it is at least 3, maybe 4 years old, and the reality of rotating disk drives is that they can fail. Som will last for 10+ years, but others can fail in as little as 3 years, depending on the luck of the draw, the physical abuse the drive receives from the environment, and how heavily the drive is used in day-to-day use.

Thanks for those suggestions. I had tried Safe Boot previously but it's been a while. So last night I tried it again. I didn't want to post the entire report from EtreCheck as it is long, but I'm happy to do that if it helps.
My confusion comes from looking at the report from Etrecheck. I got a good performance before the SafeBoot, an excellent during SafeBoot, a poor right after normal boot and an excellent later on after normal boot. My thinking with the poor performance was that things were still starting up when I ran the Etrecheck.
I might have to wait until I see apps taking a long time to open before running the Etrecheck again. But I'd be happy to post the latest report if you want to look at it.


You can try posting the EtreCheck report to, and give us a PasteBin URL link.

The fun part of a Fusion drive is that macOS uses the SSD for initial writes, then in the background migrates the file to the rotating hard disk. Some frequently used items a cached on the SSD, but other less frequently used files get kept on the rotating hard disk macOS will dynamically adjust what it puts where.

You could try DriveDX (just the demo mode) to see if it reports anything

8 Answers

Somehow I can't escape the feeling that this is a disk issue as the root cause, either in the rotating media drive or the SSD portion of the fusion drive (which DriveDX may not have visibility into).  One thing you could try would be to boot from your backup clone drive (you do have a backup clone, right? :), and note whether the slow launch times persist in that scenario. Normally apps will open slowly from an external USB drive, but I think they would be faster than 60 seconds.


That's a good idea. Definitely I have a nightly clone, in fact several backups. I have booted up from the clone, but just to make sure it works. I can try that over several days and see if it gives any clue.


Just an update. I haven't forgotten about this. I just haven't had the time to test things out using my clone. I hope to try it over the weekend.


So I finally had a chance to run off my clone today. I was using Microsoft Word and Google Chrome as test cases. Each of these took 60-90 seconds to start up on the initial open. They were a little faster on subsequent opens probably because the app was loaded into memory. This is the same sort of timings I was seeing using the internal fusion drive. So perhaps I'm seeing normal behavior and I have been spoiled over the past few years with the ssd in my Macbook and Macbook Air.

So I guess my question is, has anyone else noticed startup times for apps in the 60-90 second range using a rotation drive? Perhaps I'm looking for a problem when there isn't one. 


I launched Chrome first time in 25 seconds on my Late 2011 15" Macbook Pro with the original 750GB rotating hard disk.


Relaunch right after quitting Chrome happened in under 2 seconds.


I do not have MS-Word, so I cannot test that.


Have you used Onyx to do a more "full blooded" clean up? (I can't see it mentioned above) I'm not aware of the inner workings but all sorts of caches & linkages have to be exercised on app startup so forcing a rebuild of all of that could be helpful.


Hi Graham,

While I had not tried Onyx previously since I use things like Clean My Mac, etc, I decided to go ahead and run Onyx. I let it do its thing and then rebooted. When I tried Google Chrome, the icon bounced in the dock for 2 minutes before opening a browser window. I quit Chrome and started it again and it started within 5 seconds.

I then tried Microsoft Word and it took 40 seconds to open. Upon quitting it and opening it again it opened within 5 seconds.

I would expect since I have 16GB of memory there shouldn't be any thrashing and I don't see any. I just can't figure out what some of the apps are doing with the initial startup.

Any more thoughts?

I am contemplating a clean install when I get Catalina, if for no other reason, just to see if it makes any difference.

On the first start of an app after you have used a cleanup tool, or used Safe Mode restart, it is completely normal for it to take a long time to start. The cache files that are deleted by the cleanup methods have to be recreated. But you shouldn't see that same degree of latency after just a normal reboot (after all that is what the cache files are meant to be about - reducing the work required when the app first starts).

If you use a clean/new/second user account do you see the same symptoms? Just wondering if there might be a user permissions issue that is slowing down or preventing the proper creation of on-disk caches.


So I am cautiously optimistic. Here is what I have tried. 

Graham, I switched to my TestUser account and tried to open Chrome. Of course it opened quickly (within 10 seconds). That got me wondering if that is because I had already opened Chrome my my normal account previously. SO I rebooted the computer, logged into the TestUser account and Chrome opened right up. 

I then switched to my normal account and opened Chrome. Of course it opened within a few seconds. I tried that several times today and it opened normally.

Here is what I am thinking. I have been running Clean My Mac X (from Setapp) routinely, every week or so. By default it is cleaning out the system and user caches. I think whenever I was opening Chrome, Word or whatever, it was after running Clean My Mac so the caches were empty.  So I may have been doing this to myself., which is usually the case. 🙂

I will keep watch over the next week with normal use and see what happens. I will also check the preferences or options with Clean My Mac X. There will times when I want to clean out the caches, and other times when I do not. Hopefully I have control over that. In either case, I will keep an eye on things and report back next week.

By the way, I don't see that same behavior on my MacBook Air, but that could be because it has an SSD and the iMac has the fusion drive.

Thanks for the suggestions Graham, and everyone else.

So here is what I have observed so far. With my main account and my test account, when I open Chrome it takes about 20 seconds for it to be functional. If I quit it and open it again, it opens in about 3 seconds. After an hour, when I open it, again it takes about 20 seconds to fully open. Quitting it and opening it again, it takes about 3 seconds. So something is removing it from emory or cache after an hour. This happened while nothing else was actively being used on the computer. This doesn't feel normal to me. Any thoughts?


Those times are consistent with my tests on my 2011 Macbook Pro with rotating disk. So I think you have the performance covered.


As for being idle for an hour. You were idle, you Mac is always doing something in the background (unless you put it to sleep). So the Mac will be running daemons, agents, logging, etc... all of which will be cycling through memory during that hour, and since you did not re-launch Chrome soon after quitting, the RAM that had a copy of Chrome code and data will have been recycled for other uses.

Thanks for the double check. That helps my mind a little.
I do know there are lots of processes running in the background. But I have 16GB of memory, most of which is idle. That's what made me pause. I understand the extra memory will be used for cache as the system needs it.
Again, thanks for confirming the times you are seeing on your compute. I think everything is running normal on my machine. As a former co-worker once said to me, don't go looking for a problem if there isn't one. 🙂