Late 2015 iMac 17,1 having pausing issues

[twr7cx]

Have a Late 2015 iMac 17,1 Retina (fitted with 4 x 4GB RAM and OWC Mercury Electra 6G 500GB SSD < https://www.owcdigital.com/products/electra-6g-ssd >) that is having some lagging/freezing/pausing issues. When conducting simple tasks there is often, but at random, a delay of 20 seconds or a bit longer, in the result. Often the ‘spinning beachball’ accompanies this but not always. For example:

Click to open Safari and nothing happens for 20 seconds, then suddenly appears.

Click to open the Applications window and it opens without the icons having loaded but after 15 seconds they appear.



So far to in attempt to resolve I’ve tried the following:

Check for any Software Updates (none available – macOS Big Sur latest version)

Check for any updates in App Store

Reset SMC

Reset PRAM/NVRAM

Formatted hard drive and fresh installation of macOS Big Sur from Internet Recovery – even with a clean installation with no additional programs or apps it continues to happen.

Conducted Apple Diagnostics over the Internet (Option + D on start up) – no errors found

Run Memtest86 off bootable drive – no errors found



Any ideas on what I could try next?

 

[petsk]

Install or clone macOS to an external drive and boot from to see if the issue is the internal drive.

 

[twr7cx]

Set SuperDuper up to clone the hard drive onto an external USB hard drive. Three days it sat there for and achieved nothing. Currently have a fresh Big Sur installation going onto the external hard drive from Internet Recovery.

 

[twr7cx]

It's been a few months now but I've come back to confirm that the problem was resolved by enabling TRIM, contrary to OWC's instructions for their hard drives. For a full run down on how/why, check out:

Late 2015 iMac 17,1 having pausing issues - Apple Community

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