With the latest iMac, in particular, the iMac Late 2015 (1TB Fusion drive), I was under the impression that Trim was active. Can anyone confirm this? I was researching online, and to be honest, there is so much data about Trim, it is difficult to say if it is on by default, on the iMac Late 2015. Also, a side question. Do you use an external SSD to run your iMac software? Any limitations to doing this?