if too much redstone is active at the same time in about a single chunk then block ticks become very slow and redstone hardly works and blocks appear invisible for a while and liquids flow slowly, although entities will function normally. This happened to me in a world I imported from another device (iPod touch 6th generation) and everything worked fine on that but on this win 10 PC I experience this bug as soon as I am in the chunk/s with functioning redstone. (the redstone was aldready working when i imported it) (Redstone like flickering lights, tripwires and pressure plates connected to observers activating lights, and a constantly functioning /testfor command and some /clone commands) Everything returns to normal when half of the redstone is off.