Basic Queue which spreads out block changes over a series of ticks.

BlockQueue.java

public class BlockQueue implements Runnable {
    private final TheArtifact plugin;
    private PriorityBlockingQueue<StringBlock> queue;

    public BlockQueue(TheArtifact plugin) {
        this.plugin = plugin;
        queue = new PriorityBlockingQueue<>(20000, Comparator.comparing(o1 -> o1.priority));
        Bukkit.getScheduler().scheduleSyncRepeatingTask(plugin, this, 0, 2);
    }

    public void queueBlock(StringBlock block) {
        queue.add(block);
    }

    public synchronized void queueBlocks(Collection<StringBlock> blocks) {
        queue.addAll(blocks);
    }

    @Override
    public void run() {
        int changed = 0;
        long now = System.nanoTime();
        boolean playersOnline = !Bukkit.getOnlinePlayers().isEmpty();

        while (!queue.isEmpty()) {
            StringBlock current = queue.poll();
            current.set();
            changed++;

            //If this operation took more than 5ms, break so we don't lock the main thread for very long at a time.
            if (getElapsedFromNanos(now) >= (playersOnline ? 5 : 100)) break;
        }
    }
}