Sorry for the late update. Though I have resolved the issue a long days ago. I just checked the forum and got this post.
I was searching online about this issue why it happens during playing games. Then found one article, if anyone interested to know, can follow up this https://www.thewindowsclub.com/fix-world-of-warcraft-lag-or-latency-issues-on-pc. I guess the main reason is WoW High priority settings. So set WoW to run with High priority and also need to update all the device driver of your computer that might solve the issue.