LogSpy

Performance oriented mod that reduces log spam increasing server and client performance, tags every log line with its source mod, and intercepts unhandled exceptions.

Example below is from just launching minecraft, this ofcourse also works on servers, multiplayer and singleplayer. It not only silences logs, but also disables them from getting processed, stealing processing power from what is important: Minecraft.

With LogSpy:

Without Logspy:

I believe further explanation is not necessary.