Running Safari 11.1.2 just fine on a vintage 2007 iMac 20-inch desktop limited to El Capitan (OS 10.11.6). Memory leak problem only arises when visiting the general Yahoo website. Yahoo Mail is fine, but news or finance or anything else is bloated beyond reason, and even more so since Verizon took it over. Way too much advertising and animation and who knows what else they are doing. I watch Activity Monitor and restart Safari every time the graph goes yellow. Also have Firefox and Chrome available for any other website that becomes too problematic for Safari. Yes I know it's almost 2022 and I'd upgrade but concerned about transferring all my legacy software licenses to a new machine. And tossing all my DVDs. The 8-inch floppies and old SCSI peripherals went long ago.