Minecraft 1.13.2 is running extremely slow?

I just wanted to release my Redstone world for download and I noticed something really awful! The game itself is very fast! Only the Redstone works very slowly. Repeaters on the smallest level need 5 seconds to forward the signal. I have only one idea why this could be: I have placed about 10000 funnels. Since the processor has to calculate every single one, I think that's what it's all about. What can I do?

Minecraft 1.13 is not yet as well optimized as e.g. 1.12. But single player, it should be like that, that if it lays something, then it is all and not just the Redstone.

I think funnels do not differ much from normal blocks.

Ok thanks then I have an approximate idea what it could be. Because in other worlds in the 1.13.2 it is not so.