Okay lets begin. It's too big, make it smaller. Particles need ''modelspace'' thingy to be toggled on - this looks awfully bad on fast speed, i even suggest make two ligthining particles, one with modelspace and another without... So it will be like a storm sphere leaving lightining trail behind.
Remove useless geosets, materials bones and textures, it causes it's size increase.. Two particles can be below 1kb...
Still it looks quet good, even if it needs alittle work... GJ i guess..