NCMtnMan wrote:
Your fusion drive is the more likely issue. It's an early technology before SSD drives were affordable. You are still primarily operating off a regular hard drive. The SSD part of the fusion is very small. Most likely in the 24 gig range. These were really meant to boost boot times.
If the unit was sold as a 2 or 3 TB fusion drive it most likely is a 128 GB SSD vs the 24 GB that comes with a 1 TB fusion drive....
Easy to determine, click the apple menu upper left of the screen with OPTION pressed, select system information then look at the SATA info...
It will list the size of the SSD portion right there to read.
The thing about measuring performance by loading times - if the SSD portion is full or close to being full, the application you are loading may not reside on the SSD at the time you test it, so load the app first, then you can exit and test the load times for the second/third loading time, The Fusion drive is managed by the OS, so it moves apps and data back and forth as needed (the most used apps are on the SSD portion according to the OS.)
As an example... on my 2015 Fusion drive iMac:
Lightroom
Initial load: 14 seconds from launch to library screen full of images
Subsequent load: 6 seconds from launch to library screen full of image
Photoshop
Initial load: 15 seconds from launch to image displayed on screen
Subsequent load: 6.5 seconds from launch to image displayed on screen
Edit In Photoshop from Lightroom, image as a smart object, 7 seconds till image on screen in Photoshop
Of course disk cacheing affects the load times, as well as if other apps are running, such as Time Machine in the background