I've tested this in 18w30b, in a freshly generated world. I recreated the simple redstone circuit as shown in image 2 of the original post (repeater on 4 ticks). With the redstone off, I get about 500 fps (no V-sync). Turning the circuit on drops the frames to about 440. Lighting up the redstone cuts the drop in half, to 470.
In a populated world, this issue becomes a real problem. On my 1.12.2 multiplayer world, basic redstone has almost no noticeable impact on my fps (stable 160 fps at spawn), whereas the same map converted to 1.13 on a test server with the same specs as 1.12.2 main server, or even 18w30b in single player, consistently grinds to around 11 fps when the same redstone contraptions are activated. For this reason, we have not yet updated our server.
R3mark
I've tested this in 18w30b, in a freshly generated world. I recreated the simple redstone circuit as shown in image 2 of the original post (repeater on 4 ticks). With the redstone off, I get about 500 fps (no V-sync). Turning the circuit on drops the frames to about 440. Lighting up the redstone cuts the drop in half, to 470.
In a populated world, this issue becomes a real problem. On my 1.12.2 multiplayer world, basic redstone has almost no noticeable impact on my fps (stable 160 fps at spawn), whereas the same map converted to 1.13 on a test server with the same specs as 1.12.2 main server, or even 18w30b in single player, consistently grinds to around 11 fps when the same redstone contraptions are activated. For this reason, we have not yet updated our server.