Not sure if it's the biggest, haven't seen one bigger.

Going on the Video of 17 seconds per inventory it works out around 487,906 of them per hour.

3600 seconds in a hour, 211.8 or so inventory's per hour. 2304 items to a full inventory in Minecraft so just under 488k items/hr.

The traps far from perfect/complete, I'm sure 500k+ items per hours wouldn't be all that hard. Not sure if I'll make it much better though.

Took a while to build, I had to put in the water by hand. Only one of the cells was by hand though.

Each cell has 53 layers, each layer has 81 cacti so there's 4293 in each cell. In total there's 121 cells meaning a total of 519,453 cactus on the map.

~Daxidol