I wasn't sure where to post this as i'm not sure what it would come under... I was wondering is it possible to calculate a theoretical speed increase between 2 systems? What i'd like to find out if possible is the increase in rendering speeds, on my current system i rendered an animation to PNG in Cinema 4D (only 91 frames) and it took 3 hours 38 minutes. So currently i'm using a mid 2010 MBP 15": 2.4GHz Intel Core i5 8GB 1066 DDR3 RAM Intel HD Graphics5 256MB and NVIDIA GeForce GT 330M 256MB with automatic graphics switching 250GB SSD + 750GB 7200RPM HDD I'm looking to upgrade too: 27-inch iMac with Retina 5K display 4.0GHz quad-core Intel Core i7, Turbo Boost up to 4.2GHz 24GB 1867MHz DDR3 SDRAM 512GB Flash Storage AMD Radeon R9 M395X with 4GB video memory I don't know much about the technical side of how GPUs/CPUs work (hyper-threading etc) so upgrading from NVIDIA GeForce GT 330M 256MB to AMD Radeon R9 M395X with 4GB video memory for example doesn't mean much to me except the obvious size increase of 256MB to 4GB. If it's not possible to estimate how much faster it could render is it possible to work out roughly how much faster the system would be? sorry if it's a stupid question but like i say i don't understand this side of things and just want to get a rough idea of how much quicker the iMac would be, i know it would be better just not by how much!