When you look at blocks you can activate or get in (gravity unit, faction module, ...) you see a text hovering above it indicating that. This text seems to flicker or jump when flying at high speeds.
How to reproduce:
# make a ship that can move
# put down a faction module (or any other block that you can activate)
# fly at high speeds, enter build mode and hover your mouse over the faction module
# you'll see the "activate faction module" text jump/flicker or appear in the wrong place.