Réponse à : « MBP extremely slow after SSD Upgrade. What's wrong with my mac? »Here is what worked for me. I did a SuperDuper clone from a 256GB Samsung EVO 840 SSD to a 1TB Samsung 860EVO. After doing this the MacBook booted up ok but I noticed that there was a click delay on every action and everything seems to have somehow slowed down. Almost like the hardware know that the SSD has been removed and was trying to verify every file that was being opened. BlackMagic disk speeds didn’t reveal anything out of the ordinary. I tried to update the Samsung SSD firmware and it was already updated. I ran disk utility and did first aid. None of these solved my problem. Finally, I booted the mac into recovery (cmr+r) and did an OS reinstall. This fixed my problem. You don’t loose any of your files or applications. It simply does a reinstall. Hope this helps.