Most intensive use over time has been ripping iTunes movies to MP4 format. Seems to exercise the laptop the most. Late 2011 MBP 2.3Ghz processor, 16GB RAM, 512GB SSD ran hot as hell whenever ripping movies and the fans maxed out. Now I have a late 2013 rMPB, 2.3Ghz processor, 16GB RAM, 1TB SSD and ripping movies takes much less time (have not actually quantified it) and the rMBP runs a lot cooler I think, can hardly hear an increase in fan speed. Of course it could be down to better fan technology!!!