I understand. This scene also lags on my computer but not as much, I guess when you spawn like a hundred tracers at once it's definitely going to lag. I think the strength of the thrusters is quite weak too.
Averagecoder you can use rotation matrices, you just need to dot multiply each one by each other by the order z,y,x I'm pretty sure and then you dot multiply the combined matrix with the 3d position, that will give you the position of the point rotated around [0,0,0] by the 3 angles x,y and z and yeah I think that's how it works.