In the profiler, root.gameRenderer.level.entities.entityOutlines takes a large chunk of the performance (approximately 60% of the total working time).
To reproduce:
1. open the profiler
2. find root.gameRenderer.level.entities.entityOutlines
3. observe percentage
Can't reproduce in 15w44b
If this still an issue, please force a crash by pressing F3 + C for 10 seconds while in-game and attach the crash report (
[minecraft/crash-reports/crash-<DATE>-client.txt|http://hopper.minecraft.net/help/finding-minecraft-data-folder]
) to this ticket.