Index: src/bp-core/bp-core-functions.php
===================================================================
--- src/bp-core/bp-core-functions.php
+++ src/bp-core/bp-core-functions.php
@@ -1442,7 +1442,7 @@
 	}
 
 	// Get current time.
-	$current_time = bp_core_current_time();
+	$current_time = bp_core_current_time( true, 'timestamp' );
 
 	// Use this action to detect the very first activity for a given member.
 	if ( empty( $activity ) ) {
@@ -1460,7 +1460,7 @@
 	}
 
 	// If it's been more than 5 minutes, record a newer last-activity time.
-	if ( empty( $activity ) || ( strtotime( $current_time ) >= strtotime( '+5 minutes', $activity ) ) ) {
+	if ( empty( $activity ) || ( $current_time >= strtotime( '+5 minutes', $activity ) ) ) {
 		bp_update_user_last_activity( $user_id, $current_time );
 	}
 }
Index: src/bp-groups/bp-groups-template.php
===================================================================
--- src/bp-groups/bp-groups-template.php
+++ src/bp-groups/bp-groups-template.php
@@ -1117,7 +1117,7 @@
 		 * @param string $value Created date for the current group.
 		 * @param object $group Group object.
 		 */
-		return apply_filters( 'bp_get_group_date_created', bp_core_time_since( strtotime( $group->date_created ) ), $group );
+		return apply_filters( 'bp_get_group_date_created', bp_core_time_since( $group->date_created ), $group );
 	}
 
 /**
@@ -5434,7 +5434,7 @@
 	 *
 	 * @param string $value Formatted time since membership was requested.
 	 */
-	echo apply_filters( 'bp_group_request_time_since_requested', sprintf( __( 'requested %s', 'buddypress' ), bp_core_time_since( strtotime( $requests_template->request->date_modified ) ) ) );
+	echo apply_filters( 'bp_group_request_time_since_requested', sprintf( __( 'requested %s', 'buddypress' ), bp_core_time_since( $requests_template->request->date_modified ) ) );
 }
 
 /**
Index: src/bp-members/bp-members-template.php
===================================================================
--- src/bp-members/bp-members-template.php
+++ src/bp-members/bp-members-template.php
@@ -610,7 +610,7 @@
 		if ( ! empty( $members_template->member->last_activity ) ) {
 
 			// Calculate some times.
-			$current_time  = strtotime( bp_core_current_time() );
+			$current_time  = bp_core_current_time( true, 'timestamp' );
 			$last_activity = strtotime( $members_template->member->last_activity );
 			$still_online  = strtotime( '+5 minutes', $last_activity );
 
Index: src/bp-xprofile/bp-xprofile-activity.php
===================================================================
--- src/bp-xprofile/bp-xprofile-activity.php
+++ src/bp-xprofile/bp-xprofile-activity.php
@@ -307,7 +307,7 @@
 		 */
 		$throttle_period = apply_filters( 'bp_xprofile_updated_profile_activity_throttle_time', HOUR_IN_SECONDS * 2 );
 		$then            = strtotime( $existing['activities'][0]->date_recorded );
-		$now             = strtotime( bp_core_current_time() );
+		$now             = bp_core_current_time( true, 'timestamp' );
 
 		// Bail if throttled.
 		if ( ( $now - $then ) < $throttle_period ) {