Slow Omron NB when using USB as log storage

We are working with an omron NB Hmi and a Cp1L PLC.
These devices are monitoring and storing a temperature Log in a USB memory connected to the NB.
the problem comes when we insert the memory and then the HMI operation becomes very slow

Any ideas why this could be happening?
we tested 2 USB one was an 2.0 8GB memory and the other was a 3.1 USB which worked a little better.


but the specifications of the NB shows the USB port is an 2.0 port


Thank you very much for your help

http://www.edata.omron.com.au/eData/HMIs/NB/V122-E1-05.pdf

"When operations become slow or when a periodical process cannot be
executed as specified.
Check the available memory space on the LW9136 system memory, and secure the adequatememory. (LW9136 shows a reference value for available memory space.)
The periodically executed processes such as alarm detection, data logging, timer, or macro mayhave a longer execution interval than specified or not be executed, depending on the loads caused by screen display or communication, or the overlapping processes. Check the actual operation to adjust the load of the process."

This is in section 5 Maintenance and Abnormality Handling of the above manual.

Regards,

Thank you very much for the innformation.

going to check it!