I'm not sure if I should post this here or elsewhere such as the OS X section but here goes. System spec: late 2012 3.2 GHz i5 iMac with 16GB RAM I often leave my system downloading/uploading torrents and downloading a large number of files. After a while, the whole system starts to grind to a halt and tasks such as browsing the net appear very slow. A restart fixes the sluggishness. 1. Why is this? (Possibly due to something like caching the hard disk?) 2. Can I download/upload a lot whilst doing other tasks or will this always grind the system to a halt? 3. If the system starts becoming sluggish, is there another fix apart from restarting it?