Using a Serial node causes node-red use a lot of CPU resources

So I have Hassio running on a docker container on my raspberry pi.
I have created a simple node that gets information from the UART port located on the RPI GPIO pins:
23-12-2019 11_58_16-Home Assistant

.
The issue is that the moment I deploy CPU usage for node red skyrocket:


And I get nothing on the debug node.

Something is connected to that UART port. And even if nothing is send I don’t think that CPU usage is normal.
The module plug on the UART port is a UPS for the RPI: https://www.amazon.es/gp/product/B07HK5VGB6/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
Documentation (in chinnese): https://github.com/rcdrones/UPSPACK_V2/blob/f1a1d84c8c1bedfe848221500537972ae854cadb/GUI_py/UPS_GUI_demo.py