FPS is very low after turning on the camera

Using the multi camera example code, it is found that FPS is very low, and it is not accidental, but inevitable. Its FPS was also found to be very low during reconstruction.
Please check whether there is any problem with the published sample code. Or the bug of SDK itself.
As shown in the following picture, this picture is uploaded by others. My situation is the same as this, and the computer configuration is also consistent with the picture. D415 is used.