ZED2:Cant reach to 30FPS when it works as1080P

I used Jetson AGX Xavier as the hardware platform and download the SDK from github, set the mode to 1080P and 30FPS then ran the command “roslanuch zed_wrapper zed2.launch”. However, when I checked the frame of both left and right camera, it turned out that the frame only got to 20FPS. And when I used rosbag to record some topics published by zed2 such as “left_raw” “right raw”, the frame of of both left and right camera dropped to 15FPS. I dont know how to fix this.