So, have run some data transfer tests with different permutations. Using my old macbook connected directly to the ethernet module i can transfer up to about 16,000 led data sets a sec. Above this, the frames are incomplete. This test was done with these scenario:
90*8 leds @ 20fps
80*8 leds @ 25fps
50*8 leds @ 40fps
There was a difference in success when using different universe numbers. I found that using larger universe size and fewer universe was more successful than using lots of smaller universe ( i guess that this is to do with the packet overhead building up). An example was that 50*8leds @ 40fps worked well with universe size of 50, but not with universe of 25 (i.e 16 universe rather than 8). This test was carried out using the Pixelcontroller software for artnet output and the wiznet 820 with teensy 3.1.