Minecraft 18w09a, Minecraft 18w10a, Minecraft 18w11a, Minecraft 18w14a, Minecraft 18w14b, Minecraft 18w15a, Minecraft 18w22b, Minecraft 1.13-pre2, Minecraft 1.13-pre3, Minecraft 1.13-pre4, Minecraft 1.13-pre5, Minecraft 1.13-pre6, Minecraft 1.13-pre7, Minecraft 1.13-pre8, Minecraft 1.13-pre9, Minecraft 1.13-pre10, Minecraft 1.13, Minecraft 18w30b, Minecraft 1.13.1-pre2, Minecraft 1.13.1, Minecraft 1.13.2, Minecraft 18w46a, Minecraft 1.14.3
* Windows 7 Ultimate 64-bit
* Intel Core i7-950
* 16GB RAM
* AMD Radeon HD 6800
* Java 1.8.0_161 64-bit
* Also tested the bundled Java 1.8.0_25 64-bit
Even basic redstone contraptions are causing severe lag and framerate drops. I typically get well over 100 FPS (redstone_clock_disabled.png). To duplicate, I created a simple redstone clock that toggles a number of redstone torches and dust. While active (redstone_clock_enabled.png), this causes my framerate to drop to about 25 FPS (using the bundled javaw.exe 1.8.0_25 my framerate drops to 5 FPS).
I think this may be a lighting issue, however. I tested a redstone contraption that does not create lighting updates with a piston and rapidly flipping the lever causes no lag. If I add a redstone lamp, the lag spikes return (redstone_lamp.gif). Ninja Edit: I also get a lag spike when placing and item in a furnace and it fires up.
This may be related to the issue reported here:
MC-124086 which I believe has been erroneously marked DUPLICATE, as this bug is not present in Minecraft version 1.12.0.