import re

def getProcesses(usage=80.0, filename='performance.txt'):
    with open(filename) as f:
        lines = f.readlines()
        for line in lines:
            m = re.search('^\d+.*\s+(\d+\.\d+)\s+(\d+\.\d+).*\:', line)
            if m:
                cpu_usage = m.group(1)
                if float(cpu_usage) > usage:
                    print "CPU: ", cpu_usage
                    print line

getProcesses()

将序号和处理的文本放到一个元组里面，然后将元组存储到列表中，再按元组中的序号排列。
试试？

import psutil

imoprt 大法好