[RCARS4][Whitebox-SDK v5.x][CR52] network speed very slow?

1. The first question is whether the CR52 inside the R-Car S4 can theoretically achieve network speeds of 1G or even 2.5G. Is using such speeds for transmission beyond the intended usage range of the CR52?

2.If the answer to the first question is affirmative, then I encounter the following issues:

I want to implement a test project to measure the network speed of CR52. So, I modified the "ethernet" example in the Whitebox SDK , and added lwiperf. However, the lwiperf implemented by default in the Whitebox SDK for CR52 is extremely slow. I tried modifying the RSWITCH_MAX_NUM_CHAINS in rswitch.c for experimentation. Although the network speed increased, it still remains very slow. Could you please advise on how to improve the network speed to achieve a level closer to normal speed (on CR52)? Attached are the results of the experiment:

*Linux←→Linux(control group)

* 

exp1:  Default WhiteBoxSDK Linux←→CR52 lwiperf very slow

*

exp 2: Increasing the value of TX_RX_RING_SIZE in Rswitch.c improves the speed of the network.  

#define TX_RX_RING_SIZE     1024

exp4: Modifying the network's window size yields unreasonable data.

exp 5: Continue to increase TX_RX_RING_SIZE 2560

CR52 fw crash