webpagetest CDN detected

dedicated ip on bluehost
OS 1.5.4.1

Use a CDN for all static assets: 0/100

First Byte Time (back-end processing): 79/100
609 ms First Byte Time
405 ms Target First Byte Time

If anyone get A degree? how to improve the first byte time?

first bye time, including domain-time, server-time, network transmitting-time. so you should consider which part you can improve.

for opencart side, you can use pagecache to decrease server-time.