MacBook Pro Retina Early 2012 8GB of RAM Upgrade to High Sierra Memory Used: 7+GB Swap Used: 4GB Memory Pressure: Yellow->Red Switching tabs would cause delay and be unresponsive. Upgraded motherboard to 16GB version (because the ram is soldered onto the board) Memory Used: 7.5-11GB Swap Used: 0GB Memory Pressure: Green Everything normal. My computer was borderline unusable with 8GB of RAM on High Sierra because the OS would try to swap 4GB to the disk. With 16GB, OS feels fine, like it felt with regular Sierra. For reference, my use case is browsing the web with multiple tabs and using Office Suite; Not exactly the most demanding power user. If you don't have at least 16GB of ram with High Sierra then you are going to have a bad time.