The boot drive in my build has recently been suffering from very low transfer speeds. I ran a test on the drive and the results appear normal, but when I try to actually move/copy files its very slow. I have tried some common fixes, including enabling AHCI, and changing the Advanced Power Management through HD Sentinel. For some context the drive is a 2.5in SATA SSD by Western Digital. The model name of the drive is WDC WDS500G2BOA. I believe the drive is discontinued as I cannot find any information about it on Western Digital's Website. I will attach some images below of tests and general information about the drive.
Drive speed testing
Example of slow transfer speed
Drive info from HD Sentinel
Drive speed testing
Example of slow transfer speed