Super Slow SSD in 2017 MacBook Pro

[smoothbit]

As originally written in another thread, I've had a 2TB Sabrent SSD installed in my 2017 MacBook Pro (running macOS 12.6.2) for two years now, using this adapter card. While it was fast and behaved normally at the start, it now takes ~30 minutes to boot up, and sometimes freezes completely during use 😕

I've already tried reseting the NVRAM and SMC, and rebuilding the kextcache, but none of that helped. Does anyone have any idea as to why this might be happening? And what I can do to solve it?

 

[Honza1]

This is unique setup, so there may be some other reason also...
When my SSD became slow, it usually was either SSD failing (which may not show as errors on Disk utility) or disk was just completely full. SSDs do not like running more than ~80% full, so check the used fraction (I mean, really used, including any TimeMachine backups which may be hidden). I had antivirus software one time going crazy and filling drive with some crap to close to 100% and computer would run very, very slow.
If that is not the case, reformat drive and restore from backup. See if that fixes it.
In either case, before doing anything make sure you have backup! Preferably two, and test them.

 

[smoothbit]

Thanks for your thoughts, Honza1. There's still ~400GB free, so that's not the issue.

I cloned everything to an external drive, then reinstalled the original 128GB SSD, did a fresh install of Monteray, and everything was fast again, both booting and operation. So then I reinstalled the 2TB SSD, wiped it, and restored from the clone, and everything appears to be well again with that too, both boot up speed and using the system.

I don't know what caused it to slow down so much, and hopefully it will be fine from now on, but I'll keep an eye on it.