After placing and starting several laser (more then 30) in parallel the ore generation stops.
The Laser visual effect stays and the controlpanel of the lasers react as normal. (turn on and off and so on). No error message or crash. But the lasers do not generate ore any more and no voxel deformations happens any more.

Even after the deconstruction of most of the lasers to the amount of three lasers (which worked before placing the huge bunch) the ore generation do not restart any more.

A server restart solves the problem.

It looks like the "effiency reduction based on too much tools"-function causes the problem. The message for this behaviour appears from the fifth tool on and do not vanish after deconstruction of the fifth tool. But its not a reduction to 80% like the message said. As soon as the message appears the reduction goes to 0%. No tool can generate ore any more.