f2db8a79_OS_X_Tips_Tweaks_and_Tutorials__What_the_data_means
[Subcategory] Peak [What the data means] 
Reports on the highest total amount of memory, measured in kilobytes, that has been in use during your current session. Check this value each session to see whether the Peak value is frequently at or near the Limit value. If it is, you need to increase your memory, by either adding RAM or increasing your Page File size.
Windows Task Manager – Performance Monitoring Explained | Windows Vista,XP, Linux and OS X Tips,Tweaks and Tutorials
What the data means