Using Blackmagic Disk Speed Test on my 27" 2013 iMac, the Read/Write speeds that came out didn't go over 20 Mb/s. This makes the iMac basically unusable, as even Safari takes ages to open. We've recently had many login issues, as after putting the password it wouldn't login. After contacting the support, we run the First Aid and it said "Macintosh HD is OK". We've then completely reset the iMac and reinstalled the latest macOS. This didn't fix anything, as it still takes forever to turn on and the Read/Write speeds are still not going over 20 Mb/s. At this point I'm pretty sure all the recent problems we've had with the iMac were caused by the HD. Do you think that replacing the 1TB HD with a 1TB SSD could fix the problem? Or what other options do I have? The iMac's Apple Care expired already and I've seen companies that would replace the HD with a 1TB SSD for 499€ (circa 600$).