Chosen Solution

Works really slow and crashes

There was a recall for a bad series of SSD drives this system uses. I would recommend you visit an Apple Store to have them check it out. If its one of the defective SSD’s It should be covered under extended warranty, here’s the notice: MacBook Air Flash Storage Drive Replacement Program. While the note states MacBook Air systems, Apple later acknowledged a few MacBook Pro’s where also effected. If its not covered you’ll need to replace the SSD. Here is the best source for a replacement drive: OWC - SSD Upgrades for MacBook Pro retina models: 13" & 15" Late 2013, 2014, & 2015