diff --git a/js/swad15.226.js b/js/swad15.226.js
index 015448067..8b50ddecb 100644
--- a/js/swad15.226.js
+++ b/js/swad15.226.js
@@ -577,7 +577,7 @@ function readOldTimelineData () {
 					// Move all the LI elements in UL 'old_timeline_list' to the bottom of UL 'timeline_list'
 					var timeline = document.getElementById("timeline_list");
 					for (var i=0; i<countOldTimeline; i++)
-							timeline.appendChild(oldTimeline.firstChild);
+						timeline.appendChild(oldTimeline.firstChild);
 				}
 				
 				if (countOldTimeline < 20)	// Set to Soc_MAX_OLD_PUBS_TO_GET_AND_SHOW
diff --git a/swad_changelog.h b/swad_changelog.h
index 6862a0811..ef25bb459 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -129,13 +129,14 @@
 /****************************** Public constants *****************************/
 /*****************************************************************************/
 
-#define Log_PLATFORM_VERSION	"SWAD 15.226.7 (2016-06-19)"
+#define Log_PLATFORM_VERSION	"SWAD 15.227 (2016-06-20)"
 #define CSS_FILE		"swad15.226.css"
 #define JS_FILE			"swad15.226.js"
 
 // Number of lines (includes comments but not blank lines) has been got with the following command:
 // nl swad*.c swad*.h css/swad*.css py/swad*.py js/swad*.js soap/swad*.h sql/swad*.sql | tail -1
 /*
+        Version 15.227:   Jun 20, 2015	Query optimization in search of users. (203214 lines)
         Version 15.226.7: Jun 19, 2015	One new social network. (202969 lines)
 					1 change necessary in database:
 ALTER TABLE usr_webs CHANGE Web Web ENUM('www', '500px', 'delicious', 'deviantart', 'diaspora', 'edmodo', 'facebook', 'flickr', 'foursquare', 'github', 'gnusocial', 'googleplus', 'googlescholar', 'identica', 'instagram', 'linkedin', 'orcid', 'paperli', 'pinterest', 'quitter', 'researchgate', 'researcherid', 'scoopit', 'slideshare', 'stackoverflow', 'storify', 'tumblr', 'twitter', 'wikipedia', 'youtube') NOT NULL;
diff --git a/swad_user.c b/swad_user.c
index 8af3e5bdd..ae3f9dead 100644
--- a/swad_user.c
+++ b/swad_user.c
@@ -810,7 +810,7 @@ unsigned Usr_GetNumCrssOfUsrNotAccepted (long UsrCod)
    sprintf (Query,"SELECT COUNT(*) FROM crs_usr"
 	          " WHERE UsrCod='%ld' AND Accepted='N'",
             UsrCod);
-   return (unsigned) DB_QueryCOUNT (Query,"can not get the number of courses of a user not accepted");
+   return (unsigned) DB_QueryCOUNT (Query,"can not get the number of courses of a user");
   }
 
 /*****************************************************************************/
@@ -828,6 +828,21 @@ unsigned Usr_GetNumCrssOfUsrWithARole (long UsrCod,Rol_Role_t Role)
    return (unsigned) DB_QueryCOUNT (Query,"can not get the number of courses of a user with a role");
   }
 
+/*****************************************************************************/
+/********* Get number of courses in with a user have a given role ************/
+/*****************************************************************************/
+
+unsigned Usr_GetNumCrssOfUsrWithARoleNotAccepted (long UsrCod,Rol_Role_t Role)
+  {
+   char Query[128];
+
+   /***** Get the number of courses of a user with a role from database ******/
+   sprintf (Query,"SELECT COUNT(*) FROM crs_usr"
+                  " WHERE UsrCod='%ld' AND Role='%u' AND Accepted='N'",
+            UsrCod,(unsigned) Role);
+   return (unsigned) DB_QueryCOUNT (Query,"can not get the number of courses of a user with a role");
+  }
+
 /*****************************************************************************/
 /******* Get number of users with different role in courses of a user ********/
 /*****************************************************************************/
@@ -4075,6 +4090,235 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 		                        	 &Gbl.Usrs.LstGsts)));
   }
 
+
+#define Usr_MAX_LENGTH_QUERY_LIST_USERS (16*1024)
+
+void Usr_GetUsrsLst_new (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool Search)
+  {
+   char Query[Usr_MAX_LENGTH_QUERY_LIST_USERS+1];
+
+   /***** Build query *****/
+   if (Search && Role == Rol__GUEST_)	// Special case
+     {
+      /* Select users with no courses */
+      sprintf (Query,"SELECT UsrCod,'N',Sex"
+                     " FROM usr_data"
+		     " WHERE %s"
+		     " AND UsrCod NOT IN (SELECT UsrCod FROM crs_usr)"
+		     " ORDER BY "
+		     "Surname1,"
+		     "Surname2,"
+		     "FirstName,"
+		     "UsrCod",
+	       UsrQuery);
+     }
+   else						// Rest of cases
+      switch (Scope)
+	{
+	 case Sco_SCOPE_SYS:
+	    if (Search)
+	       /* Select users with any of their courses not accepted +
+			 users with all their courses accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr"
+			      " WHERE %s"
+			      " AND usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			UsrQuery,
+			(unsigned) Role);
+	    else
+	       /* Select users with any of their courses not accepted +
+			 users with all their courses accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr"
+			      " WHERE usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			(unsigned) Role);
+	    break;
+	 case Sco_SCOPE_CTY:
+	    if (Search)
+	       /* Select users of degrees in current country with any courses in those degrees not accepted +
+			 users of degrees in current country with all their courses in those degrees accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses,degrees,centres,institutions"
+			      " WHERE %s"
+			      " AND usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod=degrees.DegCod"
+			      " AND degrees.CtrCod=centres.CtrCod"
+			      " AND centres.InsCod=institutions.InsCod"
+			      " AND institutions.CtyCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			UsrQuery,
+			(unsigned) Role,
+			Gbl.CurrentCty.Cty.CtyCod);
+	    else
+	       /* Select users of degrees in current country with any courses in those degrees not accepted +
+			 users of degrees in current country with all their courses in those degrees accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses,degrees,centres,institutions"
+			      " WHERE usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod=degrees.DegCod"
+			      " AND degrees.CtrCod=centres.CtrCod"
+			      " AND centres.InsCod=institutions.InsCod"
+			      " AND institutions.CtyCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			(unsigned) Role,
+			Gbl.CurrentCty.Cty.CtyCod);
+	    break;
+	 case Sco_SCOPE_INS:
+	    if (Search)
+	       /* Select users of degrees in current institution with any courses in those degrees not accepted +
+			 users of degrees in current institution with all their courses in those degrees accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses,degrees,centres"
+			      " WHERE %s"
+			      " AND usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod=degrees.DegCod"
+			      " AND degrees.CtrCod=centres.CtrCod"
+			      " AND centres.InsCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			UsrQuery,
+			(unsigned) Role,
+			Gbl.CurrentIns.Ins.InsCod);
+	    else
+	       /* Select users of degrees in current institution with any courses in those degrees not accepted +
+			 users of degrees in current institution with all their courses in those degrees accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses,degrees,centres"
+			      " WHERE usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod=degrees.DegCod"
+			      " AND degrees.CtrCod=centres.CtrCod"
+			      " AND centres.InsCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			(unsigned) Role,
+			Gbl.CurrentIns.Ins.InsCod);
+	    break;
+	 case Sco_SCOPE_CTR:
+	    if (Search)
+	       /* Select users of degrees in current centre with any courses in those degrees not accepted +
+			 users of degrees in current centre with all their courses in those degrees accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses,degrees"
+			      " WHERE %s"
+			      " AND usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod=degrees.DegCod"
+			      " AND degrees.CtrCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			UsrQuery,
+			(unsigned) Role,
+			Gbl.CurrentCtr.Ctr.CtrCod);
+	    else
+	       /* Select users of degrees in current centre with any courses in those degrees not accepted +
+			 users of degrees in current centre with all their courses in those degrees accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses,degrees"
+			      " WHERE usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod=degrees.DegCod"
+			      " AND degrees.CtrCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			(unsigned) Role,
+			Gbl.CurrentCtr.Ctr.CtrCod);
+	    break;
+	 case Sco_SCOPE_DEG:
+	    if (Search)
+	       /* Select users of current degree with any courses in current degree not accepted +
+			 users of current degree with all their courses in current degree accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses"
+			      " WHERE %s"
+			      " AND usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			UsrQuery,
+			(unsigned) Role,
+			Gbl.CurrentDeg.Deg.DegCod);
+	    else
+	       /* Select users of current degree with any courses in current degree not accepted +
+			 users of current degree with all their courses in current degree accepted */
+	       sprintf (Query,"SELECT DISTINCT usr_data.UsrCod,'N' AS Accepted,usr_data.Sex"
+			      " FROM usr_data,crs_usr,courses"
+			      " WHERE usr_data.UsrCod=crs_usr.UsrCod"
+			      " AND crs_usr.Role='%u'"
+			      " AND crs_usr.CrsCod=courses.CrsCod"
+			      " AND courses.DegCod='%ld'"
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
+			(unsigned) Role,
+			Gbl.CurrentDeg.Deg.DegCod);
+	    break;
+	 case Sco_SCOPE_CRS:
+	    Usr_BuildQueryToGetUsrsLstCrs (Role,UsrQuery,Search,Query);
+	    break;
+	 default:
+	    Lay_ShowErrorAndExit ("Wrong scope.");
+	    break;
+        }
+/*
+   if (Gbl.Usrs.Me.LoggedRole == Rol_ROLE_SYS_ADM)
+      Lay_ShowAlert (Lay_INFO,Query);
+*/
+   /***** Get list of users from database *****/
+   Usr_GetListUsrs (Query,
+                    ( Role == Rol_TEACHER ? &Gbl.Usrs.LstTchs :
+		     (Role == Rol_STUDENT ? &Gbl.Usrs.LstStds :
+		                        	 &Gbl.Usrs.LstGsts)));
+  }
+
 /*****************************************************************************/
 /******************** Get list with data of administrators *******************/
 /*****************************************************************************/
@@ -5834,7 +6078,7 @@ unsigned Usr_ListUsrsFound (Rol_Role_t Role,const char *UsrQuery)
    Usr_SetUsrDatMainFieldNames ();
 
    /***** Search for teachers *****/
-   Usr_GetUsrsLst (Role,Gbl.Scope.Current,UsrQuery,true);
+   Usr_GetUsrsLst_new (Role,Gbl.Scope.Current,UsrQuery,true);
    if ((NumUsrs = LstUsrs->NumUsrs))
      {
       /***** Write heading *****/
@@ -5862,6 +6106,11 @@ unsigned Usr_ListUsrsFound (Rol_Role_t Role,const char *UsrQuery)
            {
             UsrDat.Accepted = LstUsrs->Lst[NumUsr].Accepted;
 
+            if (Role == Rol__GUEST_)
+               UsrDat.Accepted = false;
+            else
+               UsrDat.Accepted = (Usr_GetNumCrssOfUsrWithARoleNotAccepted (UsrDat.UsrCod,Role) == 0);
+
             /* Write data of this user */
             Usr_WriteRowUsrMainData (NumUsr + 1,&UsrDat,false);
 
diff --git a/swad_user.h b/swad_user.h
index 52b56bda0..6df2cd37c 100644
--- a/swad_user.h
+++ b/swad_user.h
@@ -220,6 +220,8 @@ bool Usr_CheckIfUsrIsSuperuser (long UsrCod);
 unsigned Usr_GetNumCrssOfUsr (long UsrCod);
 unsigned Usr_GetNumCrssOfUsrNotAccepted (long UsrCod);
 unsigned Usr_GetNumCrssOfUsrWithARole (long UsrCod,Rol_Role_t Role);
+unsigned Usr_GetNumCrssOfUsrWithARoleNotAccepted (long UsrCod,Rol_Role_t Role);
+
 unsigned Usr_GetNumUsrsInCrssOfAUsr (long UsrCod,Rol_Role_t UsrRole,
                                      Rol_Role_t OthersRole);
 bool Usr_CheckIfUsrSharesAnyOfMyCrs (long UsrCod);
@@ -301,6 +303,7 @@ unsigned Usr_GetNumUsrsWhoClaimToBelongToIns (long InsCod);
 unsigned Usr_GetNumUsrsWhoClaimToBelongToCtr (long CtrCod);
 unsigned Usr_GetNumberOfTeachersInCentre (long CtrCod);
 
+void Usr_GetUsrsLst_new (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool Search);
 void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t ListUsrsRange,const char *TchQuery,bool Search);
 void Usr_GetUnorderedStdsCodesInDeg (long DegCod);
 void Usr_FreeUsrsList (struct ListUsers *LstUsrs);