expected performance when encoding and decoding at the same time?

[alexheinz]

I am trying to build a video conferencing system with two Raspberry Pi 2 and rpicamsrc.

I am able to stream with an acceptable delay but if the resolution is FullHD and the frame rate is 30 fps, the performance drops to an unacceptable level.
1280x720 with 30 fps is not as bad as FullHD but the frame is also too low.
960x540 with 30 fps looks ok to me.

Here is a simplified test case with the frame counter enabled (so you can easily see frame drops) which only requires a single raspberry pi (streaming to itself).

Raspbian lite needs to be set up according to #79 to make sure that glimagesink actually works

sink (needs to be started first):
gst-launch-1.0 udpsrc port=5200 ! application/x-rtp, encoding-name=H264,payload=96 ! rtph264depay ! h264parse ! omxh264dec ! glimagesink render-rectangle="<0,0,1920,1080>"

source:
gst-launch-1.0 -v rpicamsrc preview=1 annotation-text-size=410 annotation-mode=0x00000200 fullscreen=0 preview-x=1550 preview-y=850 preview-w=320 preview-h=180 bitrate=2000000 ! 'video/x-h264, width=1920, height=1080, framerate=30/1,profile=high' ! h264parse ! rtph264pay config-interval=10 pt=96 ! udpsink host=127.0.0.1 port=5200

Is there anything I can do to improve performance (e.g. by switching to Pi3/Pi3+ or overclocking)?

Thank you for your help!