CompileTimer.cs

using System;
using UnityEditor;
using UnityEngine;

[InitializeOnLoad]
public static class EditorApplicationCompilationUtil {

	static EditorApplicationCompilationUtil() {
		EditorApplication.update += EditorApplicationCompilationUtil.OnEditorUpdate;
	}
		
	private static bool StoredCompilingState {
		get { return EditorPrefs.GetBool("EditorApplicationCompilationUtil::StoredCompilingState"); }
		set { EditorPrefs.SetBool("EditorApplicationCompilationUtil::StoredCompilingState", value); }
	}


	private static void OnEditorUpdate() {
		if (EditorApplication.isCompiling && EditorApplicationCompilationUtil.StoredCompilingState == false) {
			EditorApplicationCompilationUtil.StoredCompilingState = true;
			EditorPrefs.SetString("compileTimeStart", "" + (DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond));
		}

		if (!EditorApplication.isCompiling && EditorApplicationCompilationUtil.StoredCompilingState == true) {
			EditorApplicationCompilationUtil.StoredCompilingState = false;
			AssetDatabase.SaveAssets();

			long startCompile = long.Parse(EditorPrefs.GetString("compileTimeStart", "0"));
			Debug.Log("Compile time: " + (DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond - startCompile) + " ms.");
		}
	}
}