Extremely fast and lightweight no flicker scoreboard. 30-32 characters in versions below 1.13.

Board.java

import java.util.NoSuchElementException;

import org.bukkit.ChatColor;
import org.bukkit.scoreboard.Objective;
import org.bukkit.scoreboard.Team;
import org.bukkit.scoreboard.Scoreboard;
import org.bukkit.scoreboard.Score;

import static org.bukkit.Bukkit.getScoreboardManager;
import static org.bukkit.Bukkit.getServer;
import static org.bukkit.ChatColor.translateAlternateColorCodes;
import static org.bukkit.ChatColor.COLOR_CHAR;
import static org.bukkit.ChatColor.getLastColors;
import static org.bukkit.scoreboard.DisplaySlot.SIDEBAR;

/**
 * A 32 character no flicker scoreboard implementation, fast and lightweight.
 */
@SuppressWarnings("deprecation") public class Board {
	private static final int MAX_LINES = 15;
	private static final int MAX_CHARACTERS;
	private static final String[] BLANKS = new String[MAX_LINES];
	private final Team[] teams = new Team[MAX_LINES];
	private final Objective objective;

	static {
		MAX_CHARACTERS = !getServer().getVersion().contains("1.1") ? 16 : 64
		for (int i = 0; i < MAX_LINES; ++i)
			BLANKS[i] = new String(new char[]{COLOR_CHAR, (char) ('s' + i)});
	}

	/**
	 * Construct a new {@link TeamsScoreboard} wrapping the given {@link org.bukkit.scoreboard.Scoreboard}.
	 * 
	 * @param board
	 * 		- The {@link org.bukkit.scoreboard.Scoreboard} to wrap.
	 */
	public Board(Scoreboard board) {
		board.clearSlot(SIDEBAR);
		objective = board.registerNewObjective("sidebar", "dummy");
		objective.setDisplaySlot(SIDEBAR);
		for (int i = 0; i < MAX_LINES; i++)
			(teams[i] = board.registerNewTeam(BLANKS[i])).addEntry(BLANKS[i]);
	}
	
	/**
	 * Construct a new {@link TeamsScoreboard} wrapping the main {@link org.bukkit.scoreboard.Scoreboard}.
	 */
	public Board() { this(getScoreboardManager().getMainScoreboard()); }

	/**
	 * Sets the title to the given value.
	 *
	 * @param title
	 * 		- The new title.
	 */
	public void title(Object title) { objective.setDisplayName(title.toString()); }

	/**
	 * Sets the line at a given index to the given text and score.
	 *
	 * @param index
	 * 		- The index of the line.
	 * @param text
	 * 		- The text 32-128 characters max.
	 * @param score
	 * 		- The score to display for this line.
	 * @return - The index of the line.
	 */
	public int line(int index, String text, int score) {
		final int max = MAX_CHARACTERS, min = MAX_CHARACTERS - 1;
		final int split = text.length() < max ? 0 : text.charAt(min) == '§' ? min : max;
		final String prefix = split == 0 ? text : text.substring(0, split);
		final String suffix = split == 0 ? "" : text.substring(split);
		objective.getScore(BLANKS[index]).setScore(score);
		if (split != max) teams[index].setSuffix(suffix); else
		teams[index].setSuffix(getLastColors(prefix) + suffix);
		teams[index].setPrefix(prefix); return index;
	}

	/**
	 * Sets the line at a given index to the given text with a score of 1.
	 *
	 * @param index
	 * 		- The index of the line.
	 * @param text
	 * 		- The text. ~32 characters max.
	 * @return - The index of the line.
	 */
	public int line(int index, String text) { return line(index, text, index); }

	/**
	 * Sets the first empty line to the given text with a score of 1.
	 *
	 * @param text
	 * 		- The text. ~32 characters max.
	 * @return - The index of the line.
	 */
	public int line(String text) {
		for (int i = 0; i < MAX_LINES; i++)
			if (teams[i].getPrefix().isEmpty())
				return line(i, text);
		throw new NoSuchElementException("No empty lines");
	}


	/**
	 * Removes the line at the given index.
	 *
	 * @param index
	 * 		- The index of the line.
	 * @return - {@code true} if the line was previously set.
	 */
	public boolean remove(int index) {
		if (index >= MAX_LINES) return false;
		objective.getScoreboard().resetScores(BLANKS[index]);
		return true;
	}
}