Having some trouble with my SSD. It's a Samsung 830 256GB. Macbook Pro mid-2012 13-inch. Currently, I'm getting speeds like this With Mavericks I was got about 450MB/s reads and only 100MB/s writes so I realize this problem isn't entirely isolated to Yosemite, but there has been a significant decline since I upgraded. Trim Enabler is on and functioning correctly. I haven't been able to update my firmware on the SSD yet so that could be a contributing factor but speeds that low seem unlikely to stem from some firmware.