500 indiv addressable LEDs, one arduino. Too slow...

These LEDs have a data and a clock input. It seems like the arduino takes a while to send the data, cutting into the framerate and messing up things like fading brightness. Speed is important as I'm making a music light show.

How can I speed this up? One idea is to run a wire next to the strip and connect the data/clock in segments. Same data must be passed from the arduino but now it can be sent out in parallel instead of propagating all the way down. Is that a good/practical idea? I was using the FastLED library.

Link to datasheet of LEDs please. Code please (between code tags). And a diagram how it all is wired might also be useful (a photo or scan of a hand-drawn schematic will do if needed).