Poor performance when using nodejs.sdk upsert data

Enviroments:

CB5.0 x 1, SG1.5 x 2
All are 4CPU, 15GB Ram
and we use auth0.

After using nodejs sdk send data to CB. (because we’re migrate data from IBM Cloudant)
after that,
we get a lot of “same” logs at SG.
It says:
2017-12-15T08:06:15.395Z Auth: Saved _sync:user:d-xxxx.au.auth0.com%2F_auth0%7C5a33820150526a372c2b0cb4: &{{d-xxxx.au.auth0.com%2F_auth0%7C5a33820150526a372c2b0cb4 %!s(uint64=0) %!s(*uint16=)} { %!s(bool=false) $2a$10$QPgXNoTaeZbZBgMK3NLQPeaKv963GtC/Uf8Sj3/imyYGZ82sVjHy6 []} %!s(*auth.Authenticator=&{0xc4203e2000 0xc4201da000}) []}

with high cpu usage both on CB(~50%) & SG(~80%) about 5 hours…
my question is…

is that normal?