diff --git a/sql/cambios.sql b/sql/cambios.sql
index 3601b1e61..e90b25e96 100644
--- a/sql/cambios.sql
+++ b/sql/cambios.sql
@@ -11164,3 +11164,5 @@ SELECT TstCod,AllowTeachers,UNIX_TIMESTAMP(TstTime) AS T,NumQsts,NumQstsNotBlank
 SELECT * FROM expanded_folders WHERE UNIX_TIMESTAMP() > UNIX_TIMESTAMP(ClickTime)+'1000';
 SELECT * FROM expanded_folders WHERE ClickTime<FROM_UNIXTIME(UNIX_TIMESTAMP()-'1000');
 
+-----
+SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN (SELECT DISTINCT UsrCod FROM admin WHERE Scope='Sys' UNION SELECT DISTINCT admin.UsrCod FROM admin,institutions WHERE admin.Scope='Ins' AND admin.Cod=institutions.InsCod AND institutions.CtyCod='724') AS admin_codes ORDER BY Surname1,Surname2,FirstName,UsrCod;
diff --git a/swad_changelog.h b/swad_changelog.h
index 489d051ba..6cdf8cd82 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -100,22 +100,23 @@
 // TODO: Show guests in connected users.
 // TODO: A teacher should may confirm a student ID? In what conditions? (Necessary in order to a student can view his/her marks)
 // TODO: Put headers Content-type and Content-disposition when redirecting with Location:
-// TODO: System admin should be able to remove/edit user's mail (when he/she detects a recipient does not exists, for example)
 // TODO: When a new assignment/attendance/survey is incorrect, the second time the form is shown, it should be filled with partial data, now is always empty
 // TODO: Remove columns "first year, last year, optional, status" when listing degrees?
 // TODO: Show message indicating that mail could be in SPAM folder
 // TODO: Do not show e-mails of administrators and teachers in lists openly
 // TODO: Show nicknames of users in lists?
+// TODO: Form to register and remove system admins
 
 /*****************************************************************************/
 /****************************** Public constants *****************************/
 /*****************************************************************************/
 
-#define Log_PLATFORM_VERSION	"SWAD 15.44.1 (2015/11/23)"
+#define Log_PLATFORM_VERSION	"SWAD 15.44.2 (2015/11/23)"
 
 // 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 15.44.2:  Nov 23, 2015	Improvement of speed in list of administrators. (187819 lines)
         Version 15.44.1:  Nov 23, 2015	Fixed bug in list of administrators. (187809 lines)
         Version 15.44:    Nov 23, 2015	Changes in list of institution, centre and degree administrators. (187788 lines)
         Version 15.43.2:  Nov 22, 2015	Minor changes in CSS. (187719 lines)
diff --git a/swad_user.c b/swad_user.c
index 3dce705af..78a0f90bd 100644
--- a/swad_user.c
+++ b/swad_user.c
@@ -4148,6 +4148,8 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
    char Query[1024];
 
    /***** Build query *****/
+   // Very important: use UNION instead OR in the following queries
+   // (OR with different tables is very slow)
    switch (Scope)
      {
       case Sco_SCOPE_SYS:	// All admins
@@ -4157,23 +4159,28 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
          break;
       case Sco_SCOPE_CTY:	// System admins
 				// and admins of the institutions, centres and degrees in the current country
-         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN "
-                        "(SELECT DISTINCT admin.UsrCod"
-                        " FROM admin,institutions,centres,degrees WHERE"
-                        " admin.Scope='Sys' OR "
-                        "(admin.Scope='Ins'"
+         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN ("
+                        "SELECT UsrCod FROM admin"
+                        " WHERE Scope='Sys'"
+                        " UNION "
+                        "SELECT DISTINCT admin.UsrCod FROM admin,institutions"
+                        " WHERE admin.Scope='Ins'"
                         " AND admin.Cod=institutions.InsCod"
-                        " AND institutions.CtyCod='%ld') OR "
-                        "(admin.Scope='Ctr'"
+                        " AND institutions.CtyCod='%ld'"
+                        " UNION "
+                        "SELECT DISTINCT admin.UsrCod FROM admin,centres,institutions"
+                        " WHERE admin.Scope='Ctr'"
                         " AND admin.Cod=centres.CtrCod"
                         " AND centres.InsCod=institutions.InsCod"
-                        " AND institutions.CtyCod='%ld') OR "
-                        "(admin.Scope='Deg'"
+                        " AND institutions.CtyCod='%ld'"
+                        " UNION "
+                        "SELECT DISTINCT admin.UsrCod FROM admin,degrees,centres,institutions"
+                        " WHERE admin.Scope='Deg'"
                         " AND admin.Cod=degrees.DegCod"
                         " AND degrees.CtrCod=centres.CtrCod"
                         " AND centres.InsCod=institutions.InsCod"
-                        " AND institutions.CtyCod='%ld'))"
-                        " ORDER BY Surname1,Surname2,FirstName,UsrCod",
+                        " AND institutions.CtyCod='%ld'"
+                        ") ORDER BY Surname1,Surname2,FirstName,UsrCod",
                   Gbl.CurrentCty.Cty.CtyCod,
                   Gbl.CurrentCty.Cty.CtyCod,
                   Gbl.CurrentCty.Cty.CtyCod);
@@ -4181,19 +4188,22 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
       case Sco_SCOPE_INS:	// System admins,
 				// admins of the current institution,
 				// and admins of the centres and degrees in the current institution
-         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN "
-                        "(SELECT DISTINCT admin.UsrCod"
-                        " FROM admin,centres,degrees WHERE"
-                        " admin.Scope='Sys' OR "
-                        "(admin.Scope='Ins' AND admin.Cod='%ld') OR "
-                        "(admin.Scope='Ctr'"
+         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN ("
+                        "SELECT DISTINCT UsrCod FROM admin"
+                        " WHERE Scope='Sys' OR "
+                        " (Scope='Ins' AND Cod='%ld')"
+                        " UNION "
+                        "SELECT DISTINCT admin.UsrCod FROM admin,centres"
+                        " WHERE admin.Scope='Ctr'"
                         " AND admin.Cod=centres.CtrCod"
-                        " AND centres.InsCod='%ld') OR "
-                        "(admin.Scope='Deg'"
+                        " AND centres.InsCod='%ld'"
+                        " UNION "
+                        "SELECT DISTINCT admin.UsrCod FROM admin,degrees,centres"
+                        " WHERE admin.Scope='Deg'"
                         " AND admin.Cod=degrees.DegCod"
                         " AND degrees.CtrCod=centres.CtrCod"
-                        " AND centres.InsCod='%ld'))"
-                        " ORDER BY Surname1,Surname2,FirstName,UsrCod",
+                        " AND centres.InsCod='%ld'"
+                        ") ORDER BY Surname1,Surname2,FirstName,UsrCod",
                   Gbl.CurrentIns.Ins.InsCod,
                   Gbl.CurrentIns.Ins.InsCod,
                   Gbl.CurrentIns.Ins.InsCod);
@@ -4202,31 +4212,30 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
 				// admins of the current institution,
 				// admins and the current centre,
 				// and admins of the degrees in the current centre
-         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN "
-                        "(SELECT DISTINCT admin.UsrCod"
-                        " FROM admin,degrees WHERE"
-                        " admin.Scope='Sys' OR "
-                        "(admin.Scope='Ins' AND admin.Cod='%ld') OR "
-                        "(admin.Scope='Ctr' AND admin.Cod='%ld') OR "
-                        "(admin.Scope='Deg'"
+         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN ("
+                        "SELECT DISTINCT UsrCod FROM admin"
+                        " WHERE Scope='Sys' OR "
+                        " (Scope='Ins' AND Cod='%ld') OR"
+                        " (Scope='Ctr' AND Cod='%ld')"
+                        " UNION "
+                        "SELECT DISTINCT admin.UsrCod FROM admin,degrees"
+                        " WHERE admin.Scope='Deg'"
                         " AND admin.Cod=degrees.DegCod"
-                        " AND degrees.CtrCod='%ld'))"
-                        " ORDER BY Surname1,Surname2,FirstName,UsrCod",
+                        " AND degrees.CtrCod='%ld'"
+                        ") ORDER BY Surname1,Surname2,FirstName,UsrCod",
                   Gbl.CurrentIns.Ins.InsCod,
                   Gbl.CurrentCtr.Ctr.CtrCod,
                   Gbl.CurrentCtr.Ctr.CtrCod);
          break;
       case Sco_SCOPE_DEG:	// System admins
 				// and admins of the current institution, centre or degree
-         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data"
-                        " WHERE UsrCod IN "
-                        "(SELECT DISTINCT UsrCod"
-                        " FROM admin WHERE"
-                        " admin.Scope='Sys' OR "
-                        "(admin.Scope='Ins' AND admin.Cod='%ld') OR "
-                        "(admin.Scope='Ctr' AND admin.Cod='%ld') OR "
-                        "(admin.Scope='Deg' AND admin.Cod='%ld'))"
-                        " ORDER BY Surname1,Surname2,FirstName,UsrCod",
+         sprintf (Query,"SELECT UsrCod,'Y',Sex FROM usr_data WHERE UsrCod IN ("
+                        "SELECT DISTINCT UsrCod FROM admin"
+                        " WHERE Scope='Sys' OR "
+                        " (Scope='Ins' AND Cod='%ld') OR"
+                        " (Scope='Ctr' AND Cod='%ld') OR"
+                        " (Scope='Deg' AND Cod='%ld')"
+                        ") ORDER BY Surname1,Surname2,FirstName,UsrCod",
                   Gbl.CurrentIns.Ins.InsCod,
                   Gbl.CurrentCtr.Ctr.CtrCod,
                   Gbl.CurrentDeg.Deg.DegCod);