/gamerule randomTickSpeed influencing redstone ticks

I was testing things on redstone (delays w/ repeaters, redstone command block clock, etc...) when I just changed this command to put a randomTickSpeed to 5000.
Suddently, all my redstone circuits were "lagging", like affected by a sort of slow madness.

So, I redo the command to a 0 randomTickSpeed : All my redstone were normally functionnal like normal.

What I was expecting was :

Only crops or grass were affected by this command

What happened :

The opposite.

To replicate this :

Place a button on a block
Make a line of repeaters connected to this block
Place a redstone lamp at the end of the line
Push the button

Try it w/ other randomTickSpeed and look at the time for the redstone to reach the lamp (0 to 5000 is the most viewable (0 seems to be the normal value))