This isn't the shortest or best way, but it should allow you to follow and edit to suit your needs.
; Sort ProcessList
#include <Array.au3>
Global $sa2_ProcessList = ProcessList()
_ArrayDisplay($sa2_ProcessList, "Original")
_ArraySort($sa2_ProcessList, 0 , 1, 0, 1) ; Sort by 2nd column
_ArrayDisplay($sa2_ProcessList, "Sorted")
For $i = 1 To UBound($sa2_ProcessList) - 1
If $sa2_ProcessList[$i][1] <= 5 Then
_ArrayDelete($sa2_ProcessList, $i)
$sa2_ProcessList[0][0] -= 1
$i -= 1
Else
ExitLoop
EndIf
Next
_ArrayDisplay($sa2_ProcessList, "PIDs > 4")
$sa2_ProcessList[0][1] = $sa2_ProcessList[0][0] & " PIDs > 4"
_ArrayColDelete($sa2_ProcessList, 0)
_ArrayDisplay($sa2_ProcessList, "Just PIDs > 4")