I don't know how 10 000 IC2 generators would be not laggy, but I suspect the best way to fuel them would be to use Routers with speed boost and bandwith upgrade. I quickly tested it and one router is definitely capable of supplying 120 generators without any problems.
Dispensers are filled, to work as router connectors. Timer is set to 500 ms, to throttle energy cell (1 MJ/t) to accommodate small number of generators (120). One router probably wouldn't scale well for more than 500 generators and one energy cell crafting is enough to supply 1200 generators (75 ticks * 16 scaffolds), so I think throttling is necessary. You can make couple of this system and connect barrels through routers, to ensure planks and sticks supply.
Edit:
It may overflow sometimes, adding inline relay, regulator (to make sure router gets full stack) and tube (routers are disabled by redstone signal) should fix it. With additional diamond and void pipe, you can be 100 % sure there would be no overflow even on world/chunk loading.
Edit2:
Overflow wasn't caused by router speed, but by the fact that timer pulse is 2 tick long, with one pulse every 1 s it is working without any problems.