it not run smoothly

[XproMichael]

hello body, it's me again, my nodemcu was arrived, base on esp-12E, it works, and never crash, but one more issue is there, signal output are not smooth, only 5 seconds then will just like jailed in 3 seconds, continued loop like this way. my setting is cpu frequency 160MHz / flash size is 4M(3M spiffs), other as default.
if you can not understand I was post one video to youtube, please kindly check it, thanks so much
https://youtu.be/--pHXtD6ENs
best regards
Michael