Some may have seen earlier posts about this. 2012 MBP 15.4", 750GB spinning disk, high-res (not retina) dropped about 4 feet onto the clamshell. Running OS X El Capitan 10.11.6 beta. It's been running majorly slow. I finally decided it was time to try to reformat, so I ran disk utilities, erased and reformatted, and fresh installed El Cap 10.11.0. Rebooted and there it was. All shiny and like new. And slower than ever. Used an app to read the SMART feedback. No problems. Ran AHT (extended version) 4 times. It says all is good- no problems. I am stuck. I'm out of ideas (my knowledge here is much less than on Windows machines for such issues. Does anyone have any suggestions? I'll be upgrading to SSD once I can, but for now, I am in a bind. It's an i& 2.6Ghz with a 7500rpm drive. It shouldn't be sluggish like this.