Thank you for posting it here. Right now the Home page monitor list contains monitors across different monitor types like website, server, RDS, EC2 etc. Since they have different performance metrics sorting in home listing page would not make sense. We will take this as a feature request and add it in our road map.
However, you can still get what you asked for as a report. Each monitor type has Top N reports based on attributes. Top N report by CPU, Memory, Disk. Top N Report by ResponseTime and so on..
You can also create your own widgets with Custom Dashboard which also has Top N Widgets.
Product Manager, Site24x7