diff --git a/source3/auth/auth_util.c b/source3/auth/auth_util.c
index 78f275d8672..51164256065 100644
--- a/source3/auth/auth_util.c
+++ b/source3/auth/auth_util.c
@@ -1107,6 +1107,7 @@ static NTSTATUS make_new_server_info_guest(auth_serversupplied_info **server_inf
 	DOM_SID guest_sid;
 	bool ret;
 	char zeros[16];
+	fstring tmp;
 
 	if ( !(sampass = samu_new( NULL )) ) {
 		return NT_STATUS_NO_MEMORY;
@@ -1145,6 +1146,9 @@ static NTSTATUS make_new_server_info_guest(auth_serversupplied_info **server_inf
 	(*server_info)->user_session_key = data_blob(zeros, sizeof(zeros));
 	(*server_info)->lm_session_key = data_blob(zeros, sizeof(zeros));
 
+	alpha_strcpy(tmp, pdb_get_username(sampass), ". _-$", sizeof(tmp));
+	(*server_info)->sanitized_username = talloc_strdup(*server_info, tmp);
+
 	return NT_STATUS_OK;
 }
 
@@ -1200,6 +1204,12 @@ static auth_serversupplied_info *copy_serverinfo(auth_serversupplied_info *src)
 		return NULL;
 	}
 
+	dst->sanitized_username = talloc_strdup(dst, src->sanitized_username);
+	if (!dst->sanitized_username) {
+		TALLOC_FREE(dst);
+		return NULL;
+	}
+
 	return dst;
 }
 
diff --git a/source3/include/auth.h b/source3/include/auth.h
index a7531b35cd9..df2bed8756d 100644
--- a/source3/include/auth.h
+++ b/source3/include/auth.h
@@ -69,7 +69,15 @@ typedef struct auth_serversupplied_info {
 
 	bool was_mapped;	/* Did the username map match? */
 	char *unix_name;
-	
+
+	/*
+	 * For performance reasons we keep an alpha_strcpy-sanitized version
+	 * of the username around as long as the global variable current_user
+	 * still exists. If we did not do keep this, we'd have to call
+	 * alpha_strcpy whenever we do a become_user(), potentially on every
+	 * smb request. See set_current_user_info.
+	 */
+	char *sanitized_username;
 } auth_serversupplied_info;
 
 struct auth_context {
diff --git a/source3/include/smb.h b/source3/include/smb.h
index d1af77d1d61..47a11f51a08 100644
--- a/source3/include/smb.h
+++ b/source3/include/smb.h
@@ -1778,8 +1778,6 @@ typedef struct user_struct {
 	struct user_struct *next, *prev;
 	uint16 vuid; /* Tag for this entry. */
 
-	userdom_struct user;
-
 	char *session_keystr; /* used by utmp and pam session code.  
 				 TDB key string */
 	int homes_snum;
diff --git a/source3/lib/substitute.c b/source3/lib/substitute.c
index 62dfdb56b56..c8ad6199e8b 100644
--- a/source3/lib/substitute.c
+++ b/source3/lib/substitute.c
@@ -213,11 +213,18 @@ static const char *get_smb_user_name(void)
 /*******************************************************************
  Setup the strings used by substitutions. Called per packet. Ensure
  %U name is set correctly also.
+
+ smb_name must be sanitized by alpha_strcpy
 ********************************************************************/
 
-void set_current_user_info(const userdom_struct *pcui)
+void set_current_user_info(const char *smb_name, const char *unix_name,
+			   const char *full_name, const char *domain)
 {
-	current_user_info = *pcui;
+	fstrcpy(current_user_info.smb_name, smb_name);
+	fstrcpy(current_user_info.unix_name, unix_name);
+	fstrcpy(current_user_info.full_name, full_name);
+	fstrcpy(current_user_info.domain, domain);
+
 	/* The following is safe as current_user_info.smb_name
 	 * has already been sanitised in register_existing_vuid. */
 
diff --git a/source3/printing/printing.c b/source3/printing/printing.c
index c5fe53f0426..aa67f08d821 100644
--- a/source3/printing/printing.c
+++ b/source3/printing/printing.c
@@ -1989,7 +1989,8 @@ static bool is_owner(struct current_user *user, const char *servicename,
 		return False;
 
 	if ((vuser = get_valid_user_struct(user->vuid)) != NULL) {
-		return strequal(pjob->user, vuser->user.smb_name);
+		return strequal(pjob->user,
+				vuser->server_info->sanitized_username);
 	} else {
 		return strequal(pjob->user, uidtoname(user->ut.uid));
 	}
@@ -2438,8 +2439,10 @@ uint32 print_job_start(struct current_user *user, int snum, char *jobname, NT_DE
 
 	if ((vuser = get_valid_user_struct(user->vuid)) != NULL) {
 		fstrcpy(pjob.user, lp_printjob_username(snum));
-		standard_sub_basic(vuser->user.smb_name, vuser->user.domain, 
-				   pjob.user, sizeof(pjob.user)-1);
+		standard_sub_basic(
+			vuser->server_info->sanitized_username,
+			pdb_get_domain(vuser->server_info->sam_account),
+			pjob.user, sizeof(pjob.user)-1);
 		/* ensure NULL termination */ 
 		pjob.user[sizeof(pjob.user)-1] = '\0'; 
 	} else {
diff --git a/source3/rpc_server/srv_lsa_nt.c b/source3/rpc_server/srv_lsa_nt.c
index 8bc377b97ea..7c33bd0d4f4 100644
--- a/source3/rpc_server/srv_lsa_nt.c
+++ b/source3/rpc_server/srv_lsa_nt.c
@@ -1479,8 +1479,8 @@ NTSTATUS _lsa_GetUserName(pipes_struct *p,
 			return NT_STATUS_NO_MEMORY;
 		}
 	} else {
-		username = vuser->user.smb_name;
-		domname = vuser->user.domain;
+		username = vuser->server_info->sanitized_username;
+		domname = pdb_get_domain(vuser->server_info->sam_account);
 	}
 
 	account_name = TALLOC_ZERO_P(p->mem_ctx, struct lsa_String);
diff --git a/source3/smbd/lanman.c b/source3/smbd/lanman.c
index a3687451d5b..a2338934822 100644
--- a/source3/smbd/lanman.c
+++ b/source3/smbd/lanman.c
@@ -3340,7 +3340,7 @@ static bool api_RNetUserGetInfo(connection_struct *conn, uint16 vuid,
 	if(vuser != NULL) {
 		DEBUG(3,("  Username of UID %d is %s\n",
 			 (int)vuser->server_info->uid,
-			 vuser->user.unix_name));
+			 vuser->server_info->unix_name));
 	}
 
 	if (!str1 || !str2 || !UserName || !p) {
@@ -3413,7 +3413,9 @@ static bool api_RNetUserGetInfo(connection_struct *conn, uint16 vuid,
 
 		/* EEK! the cifsrap.txt doesn't have this in!!!! */
 		SIVAL(p,usri11_full_name,PTR_DIFF(p2,p)); /* full name */
-		strlcpy(p2,((vuser != NULL) ? vuser->user.full_name : UserName),PTR_DIFF(endp,p2));
+		strlcpy(p2,((vuser != NULL)
+			    ? pdb_get_fullname(vuser->server_info->sam_account)
+			    : UserName),PTR_DIFF(endp,p2));
 		p2 = skip_string(*rdata,*rdata_len,p2);
 		if (!p2) {
 			return False;
@@ -3503,7 +3505,9 @@ static bool api_RNetUserGetInfo(connection_struct *conn, uint16 vuid,
 		if (uLevel == 2) {
 			SIVAL(p,60,0);		/* auth_flags */
 			SIVAL(p,64,PTR_DIFF(p2,*rdata)); /* full_name */
-   			strlcpy(p2,((vuser != NULL) ? vuser->user.full_name : UserName),PTR_DIFF(endp,p2));
+			strlcpy(p2,((vuser != NULL)
+				    ? pdb_get_fullname(vuser->server_info->sam_account)
+				    : UserName),PTR_DIFF(endp,p2));
 			p2 = skip_string(*rdata,*rdata_len,p2);
 			if (!p2) {
 				return False;
@@ -3592,7 +3596,7 @@ static bool api_WWkstaUserLogon(connection_struct *conn,uint16 vuid,
 	if(vuser != NULL) {
 		DEBUG(3,("  Username of UID %d is %s\n",
 			 (int)vuser->server_info->uid,
-			 vuser->user.unix_name));
+			 vuser->server_info->unix_name));
 	}
 
 	uLevel = get_safe_SVAL(param,tpscnt,p,0,-1);
diff --git a/source3/smbd/password.c b/source3/smbd/password.c
index 5e2e713d439..a872ea2b489 100644
--- a/source3/smbd/password.c
+++ b/source3/smbd/password.c
@@ -253,40 +253,36 @@ int register_existing_vuid(uint16 vuid,
 			DATA_BLOB response_blob,
 			const char *smb_name)
 {
-	user_struct *vuser = get_partial_auth_user_struct(vuid);
+	fstring tmp;
+	user_struct *vuser;
+
+	vuser = get_partial_auth_user_struct(vuid);
 	if (!vuser) {
 		goto fail;
 	}
 
 	/* Use this to keep tabs on all our info from the authentication */
-	vuser->server_info = server_info;
-
-	/* Ensure that the server_info will disappear with
-	 * the vuser it is now attached to */
-
-	talloc_steal(vuser, vuser->server_info);
-
-	fstrcpy(vuser->user.unix_name, server_info->unix_name);
+	vuser->server_info = talloc_move(vuser, &server_info);
 
 	/* This is a potentially untrusted username */
-	alpha_strcpy(vuser->user.smb_name, smb_name, ". _-$",
-		sizeof(vuser->user.smb_name));
+	alpha_strcpy(tmp, smb_name, ". _-$", sizeof(tmp));
 
-	fstrcpy(vuser->user.domain, pdb_get_domain(server_info->sam_account));
-	fstrcpy(vuser->user.full_name,
-	pdb_get_fullname(server_info->sam_account));
+	vuser->server_info->sanitized_username = talloc_strdup(
+		server_info, tmp);
 
 	DEBUG(10,("register_existing_vuid: (%u,%u) %s %s %s guest=%d\n",
-			(unsigned int)vuser->server_info->uid,
-			(unsigned int)vuser->server_info->gid,
-			vuser->user.unix_name, vuser->user.smb_name,
-			vuser->user.domain, vuser->server_info->guest ));
+		  (unsigned int)vuser->server_info->uid,
+		  (unsigned int)vuser->server_info->gid,
+		  vuser->server_info->unix_name,
+		  vuser->server_info->sanitized_username,
+		  pdb_get_domain(vuser->server_info->sam_account),
+		  vuser->server_info->guest ));
 
 	DEBUG(3, ("register_existing_vuid: User name: %s\t"
-		"Real name: %s\n", vuser->user.unix_name,
-		vuser->user.full_name));
+		  "Real name: %s\n", vuser->server_info->unix_name,
+		  pdb_get_fullname(vuser->server_info->sam_account)));
 
-	if (!server_info->ptok) {
+	if (!vuser->server_info->ptok) {
 		DEBUG(1, ("register_existing_vuid: server_info does not "
 			"contain a user_token - cannot continue\n"));
 		goto fail;
@@ -294,7 +290,7 @@ int register_existing_vuid(uint16 vuid,
 
 	DEBUG(3,("register_existing_vuid: UNIX uid %d is UNIX user %s, "
 		"and will be vuid %u\n", (int)vuser->server_info->uid,
-		 vuser->user.unix_name, vuser->vuid));
+		 vuser->server_info->unix_name, vuser->vuid));
 
 	next_vuid++;
 	num_validated_vuids++;
@@ -316,7 +312,7 @@ int register_existing_vuid(uint16 vuid,
 
 	if (!vuser->server_info->guest) {
 		vuser->homes_snum = register_homes_share(
-			vuser->user.unix_name);
+			vuser->server_info->unix_name);
 	}
 
 	if (srv_is_signing_negotiated() && !vuser->server_info->guest &&
@@ -327,7 +323,12 @@ int register_existing_vuid(uint16 vuid,
 	}
 
 	/* fill in the current_user_info struct */
-	set_current_user_info( &vuser->user );
+	set_current_user_info(
+		vuser->server_info->sanitized_username,
+		vuser->server_info->unix_name,
+		pdb_get_fullname(vuser->server_info->sam_account),
+		pdb_get_domain(vuser->server_info->sam_account));
+
 	return vuser->vuid;
 
   fail:
diff --git a/source3/smbd/process.c b/source3/smbd/process.c
index 5946989ae75..ab737a89a7e 100644
--- a/source3/smbd/process.c
+++ b/source3/smbd/process.c
@@ -1387,7 +1387,13 @@ static connection_struct *switch_message(uint8 type, struct smb_request *req, in
 		if(session_tag != UID_FIELD_INVALID) {
 			vuser = get_valid_user_struct(session_tag);
 			if (vuser) {
-				set_current_user_info(&vuser->user);
+				set_current_user_info(
+					vuser->server_info->sanitized_username,
+					vuser->server_info->unix_name,
+					pdb_get_fullname(vuser->server_info
+							 ->sam_account),
+					pdb_get_domain(vuser->server_info
+						       ->sam_account));
 			}
 		}
 	}
diff --git a/source3/smbd/service.c b/source3/smbd/service.c
index 7b0fdc89767..ff69fc4029f 100644
--- a/source3/smbd/service.c
+++ b/source3/smbd/service.c
@@ -724,11 +724,12 @@ static connection_struct *make_connection_snum(int snum, user_struct *vuser,
 				      return NULL;
 			}
 		} else {
-			if (!user_ok_token(vuser->user.unix_name,
+			if (!user_ok_token(vuser->server_info->unix_name,
 					   vuser->server_info->ptok, snum)) {
 				DEBUG(2, ("user '%s' (from session setup) not "
 					  "permitted to access this share "
-					  "(%s)\n", vuser->user.unix_name,
+					  "(%s)\n",
+					  vuser->server_info->unix_name,
 					  lp_servicename(snum)));
 				conn_free(conn);
 				*status = NT_STATUS_ACCESS_DENIED;
@@ -738,8 +739,8 @@ static connection_struct *make_connection_snum(int snum, user_struct *vuser,
 		conn->vuid = vuser->vuid;
 		conn->uid = vuser->server_info->uid;
 		conn->gid = vuser->server_info->gid;
-		string_set(&conn->user,vuser->user.unix_name);
-		fstrcpy(user,vuser->user.unix_name);
+		string_set(&conn->user,vuser->server_info->unix_name);
+		fstrcpy(user,vuser->server_info->unix_name);
 		guest = vuser->server_info->guest;
 	} else if (lp_security() == SEC_SHARE) {
 		NTSTATUS status2;
diff --git a/source3/smbd/session.c b/source3/smbd/session.c
index 2b964d828f9..5e5a184efaf 100644
--- a/source3/smbd/session.c
+++ b/source3/smbd/session.c
@@ -164,7 +164,7 @@ bool session_claim(user_struct *vuser)
 		hostname = client_addr(get_client_fd(),addr,sizeof(addr));
 	}
 
-	fstrcpy(sessionid.username, vuser->user.unix_name);
+	fstrcpy(sessionid.username, vuser->server_info->unix_name);
 	fstrcpy(sessionid.hostname, hostname);
 	sessionid.id_num = i;  /* Only valid for utmp sessions */
 	sessionid.pid = pid;
diff --git a/source3/smbd/uid.c b/source3/smbd/uid.c
index 0b87b93636c..3779c3f6088 100644
--- a/source3/smbd/uid.c
+++ b/source3/smbd/uid.c
@@ -97,12 +97,14 @@ static bool check_user_ok(connection_struct *conn, user_struct *vuser,int snum)
 		}
 	}
 
-	if (!user_ok_token(vuser->user.unix_name, vuser->server_info->ptok,
+	if (!user_ok_token(vuser->server_info->unix_name,
+			   vuser->server_info->ptok,
 			   snum))
 		return(False);
 
 	readonly_share = is_share_read_only_for_token(
-		vuser->user.unix_name, vuser->server_info->ptok, SNUM(conn));
+		vuser->server_info->unix_name, vuser->server_info->ptok,
+		SNUM(conn));
 
 	token = conn->nt_user_token ?
 		conn->nt_user_token : vuser->server_info->ptok;
@@ -132,7 +134,7 @@ static bool check_user_ok(connection_struct *conn, user_struct *vuser,int snum)
 	ent->read_only = readonly_share;
 
 	ent->admin_user = token_contains_name_in_list(
-		vuser->user.unix_name, NULL, vuser->server_info->ptok,
+		vuser->server_info->unix_name, NULL, vuser->server_info->ptok,
 		lp_admin_users(SNUM(conn)));
 
 	conn->read_only = ent->read_only;
@@ -188,7 +190,8 @@ bool change_to_user(connection_struct *conn, uint16 vuid)
 	if ((vuser) && !check_user_ok(conn, vuser, snum)) {
 		DEBUG(2,("change_to_user: SMB user %s (unix user %s, vuid %d) "
 			 "not permitted access to share %s.\n",
-			 vuser->user.smb_name, vuser->user.unix_name, vuid,
+			 vuser->server_info->sanitized_username,
+			 vuser->server_info->unix_name, vuid,
 			 lp_servicename(snum)));
 		return False;
 	}