The bug

When there are large numbers of ticking block entities a lot of time is spent calling the class.getSimpleName() for the profiler, even though the profiler is not active.

Steps to reproduce

1. Create a new superflat world and /tp 0 ~ 0
2. Create a lot of ticking block entities: /fill 0 ~ 0 100 ~2 100 minecraft:furnace

Sampling results looks like this: getSimpleName.png

Code analysis (using MCP names)

In World.java there is a profiler section around each Block Entity's update call.

this.theProfiler.startSection(tileentity.getClass().getSimpleName());
((ITickable)tileentity).update();
this.theProfiler.endSection();

Internally, profiler code is wrapped in if (this.profilingEnabled) statements, but this call to getSimpleName() is not, and it can have an impact.