Minecraft lags tremendously when near large amounts of moving water (waterfalls).
This bug DID NOT occur in 1.6.2 or 1.6.4. It started happening immediately upon upgrade to 1.7.2.
What I expected to happen was...:
Smooth game experience. With VSYNC on, I typically get 40-60 FPS pretty solid, and with it off I can hit up to 120.
What actually happened was...:
Whenever I get near large quantities of moving water (waterfall down a mountain, etc), I get tremendous lag. I can lag for multiple seconds at 0FPS.
I teleported another player to my location and he experienced the same massive lag I do. It appears to be clientside lag, not server lag. I never crash or get kicked off.
Steps to Reproduce:
1. Go to a mountain
2. Create a large number of waterfalls down the side by putting water at the top
3. Look at the waterfalls and move your camera around (walking is not necessary)
4. Lag like crazy.
Using shift-F3, root.tick.level.chunkCache.recheckGaps accounts for a majority of my CPU when this bug is occurring. It's normally a very small part of my CPU usage.
Happy to provide my worldfile if it'll help, but it's 100MB compressed.
As a Java developer, I'd also be interested in helping Mojang optimize performance in general. Feel free to contact me if you need any help.
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kumasasa
Please force a crash by pressing F3 + C for 10 seconds while in-game and attach the crash report ([minecraft|http://hopper.minecraft.net/help/finding-minecraft-data-folder]/crash-reports/crash-<DATE>-client.txt) here.
and
Please attach the complete output of the "Development console" tab of the launcher.
Click the text, press CTRL-A to select all, then CTRL-C to copy, and CTRL-V to paste in a comment on this ticket.
If the launcher closes after game start, please edit your profile and select "Launcher visibility" then, "Keep the launcher open".
Both are attached.
I just created an amplified world and filled it with waterfalls to try to reproduce the bug. I was not successful. Please let me know if you need the world file (or want access to my server) to reproduce this. It happens on all clients that connect.