Introduction to Network Trace Analysis 3: TCP Performance

Hi will:

  The is great explain. I can not understand below,Could you explain more ?

"Again, we have another packet dropped. So what? Looking in Wireshark and filtering on the tcp.port == 49713 && tcp.analysis.retransmission we see that only 8041 out of 554433 packets were retransmitted this works out to 1.5%. "

"anything over 0.5% packet loss you will see severe performance degradation"

Q1 If the network status is stable and good. the retransmitted rate should lower than 0.5 %?

Q2 .Why  over 0.5% ,severe performance degradation?