オリジナル投稿者： Steve Godun ,
Unless your “humidity” is the rough equivalent of leaving your MacBook inside your bathroom with a hot shower running all day, the odds are very against humidity being the culprit. My first guess would be a failing SSD. Several of the symptoms you’ve mentioned — slow boot, slow login, etc — are indicative of this. I would try opening the bottom case and removing the SSD drive inside. Then close it up, connect a USB3 drive to your MacBook, launch internet recovery (COMMAND-OPTION-R at startup), then install the OS to the USB3 drive and boot from that. If your performance issues go away then you '''may''' be looking at a failing SSD. If you’re lucky then replacing the SSD would solve your problem, but there’s also the possibility that the motherboard itself is having an issue communicating with the SSD drive in which case replacing the SSD would not solve your problem.