2-Channel CAN-BUS(FD) Shield for Raspberry Pi Maximum busload accepted

I am trying to log data from CAN bus (both standard and FD in separate applications) and I am experiencing gaps in these logs.
I am using baudrate 500000 for CAN and baudrate 500000 and dbaudrate 2000000 for CAN FD.
I am receiving messages at about 2KHz (average of 2 frames/ms) and canbusload can0@500000 is 48% average.

Sometimes I am getting 1 to 15ms gaps in the log files so I am losing data.
Has someone experience something similar?
Do you know/tested what is maximum busload Raspberry Pi can process?

Thank you.