It's not that bad, on my laptop the trail adds about 5-10% to cpu utilization, gpu is at 0%. On a very old phone it adds 15-25% to cpu.
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You can decrease fade out time, this will make the trail shorter, reduce the number of trail sprites and improve performance. You can also spawn trail sprite not on every step, for example skipping 2 in 3 steps.
Another solution is to use just one object for each trail line, changing its width on every tick instead of fading, but this may be a bit more complicated.