So I emailed Crucial and this is what they said. (I didn't do anything else yet just in case the drive was failing; I didn't want to exacerbate the problem.) I'm going to try it just in case and see what happens. Hopefully this can help other people out if they encounter the same problem. I do have Trim and "Put hard disks to sleep when possible" selected already though.
"Thank you for contacting us. The behavior you are describing is consistent with TRIM commands not executing on the drive (which may result from lots of writing and rewriting, especially OS installs, not done on the OS level). You may have TRIM enabled, however it is likely there is an interference preventing TRIM from reaching the drive. The accumulation of 'junk' data from file deletions, even reformats, basically clogs up the drive and reduces or sometimes even halts performance and can even dismount the drive. A secondary feature called Garbage Collection activates when the drive is powered, but has no data throughput, for an extended period, and does background cleanup on our SSDs which can make up for the lack of TRIM.
If this is the cause of your drive's behavior, a period of idling the drive without any data being written or read actively will improve its performance. We recommend you perform this idle period on a desktop computer because it allows you to only connect the SATA power connection. However, a USB enclosure with an external power source will also work. A laptop computer will also work, but youll have to connect the drive and navigate to the systems BIOS menu. (Please refer to your system manufacturers documentation on how to access the BIOS.)
For laptops, we dont recommended using a USB enclosure powered via USB; dedicated AC power is preferable. In addition, Apple users must hold the Option key while they power on the system (with the SSD installed). This will boot the Mac to the Startup Manager screen. The Startup Manager screen works like the BIOS screen on a laptop, in that it gives the drive power without any data throughput. An alternative Apple method is to close all open programs (including background processes) after startup and idle on your desktop. Just power the drive and let it sit, preferably overnight, but even a few hours should improve performance if this is the cause of your drive's erratic performance, though full Garbage Collection takes 8-24 hours and should be resumed when you can be without that system for an extended period.
To prevent the SSD performance degrading again, you can make adjustments to your power settings:
- Go to System Preferences
- Go to Energy Saver
- Make sure 'Put the hard disk(s) to sleep when possible' is unchecked. "