diff --git a/10up-experience.php b/10up-experience.php
index 533ffdc..b4ca8b1 100644
--- a/10up-experience.php
+++ b/10up-experience.php
@@ -75,19 +75,19 @@ function( $plugin_info, $http_response = null ) {
 define( 'TENUP_EXPERIENCE_IS_NETWORK', (bool) $network_activated );
 
 if ( ! defined( 'TENUP_DISABLE_BRANDING' ) || ! TENUP_DISABLE_BRANDING ) {
-	AdminCustomizations\Customizations::instance()->setup();
+	AdminCustomizations\Customizations::instance();
 }
 
-API\API::instance()->setup();
-Authentication\Usernames::instance()->setup();
-Authors\Authors::instance()->setup();
-Gutenberg\Gutenberg::instance()->setup();
-Headers\Headers::instance()->setup();
-Plugins\Plugins::instance()->setup();
-PostPasswords\PostPasswords::instance()->setup();
-SupportMonitor\Monitor::instance()->setup();
-SupportMonitor\Debug::instance()->setup();
-Notifications\Welcome::instance()->setup();
+API\API::instance();
+Authentication\Usernames::instance();
+Authors\Authors::instance();
+Gutenberg\Gutenberg::instance();
+Headers\Headers::instance();
+Plugins\Plugins::instance();
+PostPasswords\PostPasswords::instance();
+SupportMonitor\Monitor::instance();
+SupportMonitor\Debug::instance();
+Notifications\Welcome::instance();
 
 /**
  * We load this later to make sure there are no conflicts with other plugins.
@@ -95,8 +95,8 @@ function( $plugin_info, $http_response = null ) {
 add_action(
 	'plugins_loaded',
 	function() {
-		Authentication\Passwords::instance()->setup();
-		SSO\SSO::instance()->setup();
+		Authentication\Passwords::instance();
+		SSO\SSO::instance();
 	}
 );
 
diff --git a/includes/classes/SupportMonitor/DBQueryMonitor.php b/includes/classes/SupportMonitor/DBQueryMonitor.php
new file mode 100644
index 0000000..e22c582
--- /dev/null
+++ b/includes/classes/SupportMonitor/DBQueryMonitor.php
@@ -0,0 +1,496 @@
+<?php
+/**
+ * Database Queries Monitor. A submodule of Support Monitor to report heavy SQL queries executed on staging.
+ *
+ * This feature is turned off by default.
+ * For performance reasons, it is only available in production environments by default, but that
+ * can be changed using `add_filter( 'tenup_experience_disable_query_monitor', '__return_false' );`
+ *
+ * The original purpose of this feature is to log any heavy SQL query performed, for example,
+ * during a plugins upgrade. These are the queries logged:
+ * - All create, alter, truncate, drop queries
+ * - Insert, delete, update, and replace queries without a nested select and bigger than 20000 chars
+ * - Transients and options operations are ignored by default
+ *
+ * Additional checks can be created using the `tenup_experience_log_query` filter.
+ *
+ * @since  x.x
+ * @package 10up-experience
+ */
+
+namespace TenUpExperience\SupportMonitor;
+
+/**
+ * DBQueryMonitor class
+ */
+class DBQueryMonitor {
+
+	/**
+	 * The transient name
+	 *
+	 * This transient stores all the queries logged.
+	 */
+	const TRANSIENT_NAME = 'tenup_experience_db_queries';
+
+	/**
+	 * Minimum size of insert, delete, update, and replace queries to be logged.
+	 * Queries with a nested select in it will always be logged.
+	 *
+	 * CUD instead of CRUD because select/(R)ead queries are not logged.
+	 */
+	const CUD_QUERY_SIZE = 20000;
+
+	/**
+	 * Max. size of the data stored.
+	 */
+	const STORE_MAX_SIZE = MB_IN_BYTES;
+
+	/**
+	 * Max. size of the data to be sent to the API.
+	 */
+	const SEND_API_MAX_SIZE = MB_IN_BYTES;
+
+	/**
+	 * Category/score of a query.
+	 */
+	const QUERY_CATEGORIES = [
+		'high'   => 1,
+		'medium' => 2,
+		'low'    => 3,
+	];
+
+	/**
+	 * Setup module
+	 */
+	public function setup() {
+		if ( ! $this->is_enabled() ) {
+			return;
+		}
+
+		if ( TENUP_EXPERIENCE_IS_NETWORK ) {
+			add_action( 'network_admin_menu', [ $this, 'register_network_menu' ] );
+		} else {
+			add_action( 'admin_menu', [ $this, 'register_menu' ] );
+		}
+
+		add_action( 'admin_init', [ $this, 'empty_queries' ] );
+
+		add_filter( 'query', [ $this, 'maybe_log_query' ] );
+	}
+
+	/**
+	 * Utilitary function to check if the feature is available to be enabled or not.
+	 *
+	 * @return boolean
+	 */
+	public function is_available() {
+		$is_production = 'no' === Monitor::instance()->get_setting( 'production_environment' );
+
+		/**
+		 * Filter if the Query Monitor should be available. Defaults to false on non-production environments.
+		 *
+		 * If it is available, it's still needed to enable the feature in the dashboard. Having it enabled
+		 * does not mean all queries will be logged, as they will be checked as being
+		 * heavy or not first.
+		 *
+		 * @since  x.x
+		 * @hook tenup_experience_disable_query_monitor
+		 * @param  {bool} $should_log Whether Query Monitor should be enabled.
+		 * @return {bool} New value
+		 */
+		return apply_filters( 'tenup_experience_disable_query_monitor', $is_production );
+	}
+
+	/**
+	 * Return whether the submodule is enabled or not.
+	 *
+	 * @return boolean
+	 */
+	public function is_enabled() {
+		$is_enabled = 'yes' === Monitor::instance()->get_setting( 'enable_db_query_monitor' );
+
+		return $this->is_available() && $is_enabled;
+	}
+
+	/**
+	 * Registers the Query Monitor link under the 'Tools' menu
+	 *
+	 * @since x.x
+	 */
+	public function register_menu() {
+		add_submenu_page(
+			'tools.php',
+			esc_html__( '10up Query Monitor', 'tenup' ),
+			esc_html__( '10up Query Monitor', 'tenup' ),
+			'manage_options',
+			'tenup_query_monitor',
+			[ $this, 'queries_list_screen' ]
+		);
+	}
+
+	/**
+	 * Registers the Query Monitor link under the network settings
+	 *
+	 * @since x.x
+	 */
+	public function register_network_menu() {
+		add_submenu_page(
+			'settings.php',
+			esc_html__( '10up Query Monitor', 'tenup' ),
+			esc_html__( '10up Query Monitor', 'tenup' ),
+			'manage_network_options',
+			'tenup_query_monitor',
+			[ $this, 'queries_list_screen' ]
+		);
+	}
+
+	/**
+	 * Output the queries screen
+	 *
+	 * @since x.x
+	 */
+	public function queries_list_screen() {
+		$queries_per_date = $this->get_categorized_queries();
+		$status_names     = array_flip( self::QUERY_CATEGORIES );
+		?>
+
+		<div class="wrap">
+			<h2><?php esc_html_e( 'Query Monitor', 'tenup' ); ?></h2>
+
+			<p>
+				<a href="<?php echo esc_url( add_query_arg( 'tenup_query_monitor_nonce', wp_create_nonce( 'tenup_qm_empty_action' ) ) ); ?>" class="button"><?php esc_html_e( 'Empty Queries', 'tenup' ); ?></a>
+			</p>
+
+			<?php if ( ! empty( $queries_per_date ) ) : ?>
+				<?php foreach ( $queries_per_date as $date => $queries ) : ?>
+					<h3><?php echo esc_html( date_i18n( 'F j, Y', strtotime( $date ) ) ); ?></h3>
+					<?php foreach ( $queries as $query ) : ?>
+						<div>
+							<strong><?php esc_html_e( 'Category:', 'tenup' ); ?></strong> <?php echo esc_html( $status_names[ $query['status'] ] ); ?><br>
+							<strong><?php esc_html_e( 'Query:', 'tenup' ); ?></strong> <code><?php echo esc_html( $query['query'] ); ?></code><br>
+							<strong><?php esc_html_e( 'File:', 'tenup' ); ?></strong> <?php echo esc_html( $query['file'] ); ?><br>
+							<strong><?php esc_html_e( 'Line:', 'tenup' ); ?></strong> <?php echo esc_html( $query['line'] ); ?><br>
+							<strong><?php esc_html_e( 'Count:', 'tenup' ); ?></strong> <?php echo esc_html( $query['count'] ); ?><br><br>
+						</div>
+					<?php endforeach; ?>
+				<?php endforeach; ?>
+			<?php else : ?>
+				<p><?php esc_html_e( 'No queries.', 'tenup' ); ?></p>
+			<?php endif; ?>
+		</div>
+		<?php
+	}
+
+	/**
+	 * Empty queries
+	 *
+	 * @since x.x
+	 */
+	public function empty_queries() {
+		if ( empty( $_GET['tenup_query_monitor_nonce'] ) || ! wp_verify_nonce( $_GET['tenup_query_monitor_nonce'], 'tenup_qm_empty_action' ) ) {
+			return;
+		}
+
+		if ( TENUP_EXPERIENCE_IS_NETWORK ) {
+			delete_site_transient( self::TRANSIENT_NAME );
+
+			wp_safe_redirect( network_admin_url( 'settings.php?page=tenup_query_monitor' ) );
+		} else {
+			delete_transient( self::TRANSIENT_NAME );
+
+			wp_safe_redirect( admin_url( 'tools.php?page=tenup_query_monitor' ) );
+		}
+	}
+
+	/**
+	 * Conditionally log a query
+	 *
+	 * Get all potential heavy queries (CREATE, ALTER, etc.) and store it,
+	 * ignoring transients and options by default.
+	 *
+	 * @param string $query The SQL query.
+	 * @return string
+	 */
+	public function maybe_log_query( $query ) {
+		global $wpdb;
+
+		if ( ! preg_match( '/^\s*(create|alter|truncate|drop|insert|delete|update|replace)\s/i', $query ) ) {
+			return $query;
+		}
+
+		if ( false !== strpos( $query, 'transient_' ) ) {
+			return $query;
+		}
+
+		if ( false !== strpos( $query, $wpdb->options ) ) {
+			return $query;
+		}
+
+		// For INSERT, DELETE, UPDATE, and REPLACE queries, only log nested SELECTs or big queries.
+		if ( preg_match( '/^\s*(insert|delete|update|replace)\s/i', $query ) &&
+			false === strpos( $query, 'select' ) &&
+			strlen( $query ) < self::CUD_QUERY_SIZE ) {
+			return $query;
+		}
+
+		/**
+		 * Filter if a specific SQL query should be logged. Defaults to true.
+		 *
+		 * If code reached this filter, it means the query already passed the plugin default checks.
+		 *
+		 * @since  x.x
+		 * @hook tenup_experience_log_query
+		 * @param  {bool} $should_log Whether the query should be logged or not.
+		 * @param  {string} $query The SQL query.
+		 * @return {bool} New value of $should_log
+		 */
+		if ( apply_filters( 'tenup_experience_log_query', true, $query ) ) {
+			$this->log_query( $query );
+		}
+
+		return $query;
+	}
+
+	/**
+	 * Generate the response for the Support Monitor.
+	 *
+	 * Also, as this is called periodically, removes from the transient all old queries.
+	 *
+	 * @see cleanup_queries()
+	 *
+	 * @return bool Whether queries were logged recently or not.
+	 */
+	public function get_report() {
+		$this->cleanup_queries();
+
+		$all_queries_stored = $this->get_categorized_queries();
+		$queries_to_send    = $all_queries_stored;
+		$response           = [
+			'trimmed' => false,
+			'queries' => [],
+		];
+
+		$queries_str = wp_json_encode( $all_queries_stored );
+		while ( mb_strlen( $queries_str ) > self::SEND_API_MAX_SIZE ) {
+			array_shift( $queries_to_send );
+			$response['trimmed'] = true;
+			$queries_str         = wp_json_encode( $queries_to_send );
+		}
+
+		$response['queries'] = $all_queries_stored;
+
+		return $response;
+	}
+
+	/**
+	 * Remove old queries from the transient.
+	 *
+	 * @return void
+	 */
+	protected function cleanup_queries() {
+		$date_limit = strtotime( '7 days ago' );
+
+		$stored_queries = array_filter(
+			$this->get_transient(),
+			function ( $query_date ) use ( $date_limit ) {
+				return strtotime( $query_date ) > $date_limit;
+			},
+			ARRAY_FILTER_USE_KEY
+		);
+
+		$this->set_transient( $stored_queries );
+	}
+
+	/**
+	 * Log/store a SQL query
+	 *
+	 * Queries are stored like:
+	 *
+	 *    'YYYY-MM-DD' => [
+	 *        'a5be998feee8968155052c4d332a7223' => [ // md5 of file:line:query
+	 *            'query' => 'ALTER TABLE wp_my_db_heavy_plugin CHANGE COLUMN `id` id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT',
+	 *            'file' => '/var/www/html/wp-content/plugins/my-db-heavy-plugin/my-db-heavy-plugin.php',
+	 *            'line' => 53,
+	 *            'count' => 3, // how many times the same query was sent in a day
+	 *        ]
+	 *    ]
+	 *
+	 * @param string $query The SQL query.
+	 */
+	protected function log_query( $query ) {
+		static $stored_queries;
+		if ( empty( $stored_queries ) ) {
+			$stored_queries = $this->get_transient( self::TRANSIENT_NAME ) ?? [];
+		}
+
+		$current_date = date_i18n( 'Y-m-d' );
+
+		if ( ! isset( $stored_queries[ $current_date ] ) ) {
+			$stored_queries[ $current_date ] = [];
+		}
+
+		$main_caller = $this->find_main_caller();
+
+		$key = md5(
+			$main_caller['file'] . ':' .
+			$main_caller['line'] . ':' .
+			$query
+		);
+
+		if ( isset( $stored_queries[ $current_date ][ $key ] ) ) {
+			$stored_queries[ $current_date ][ $key ]['count']++;
+		} else {
+			$stored_queries[ $current_date ][ $key ] = [
+				'query' => $this->escape_query( $query ),
+				'file'  => $main_caller['file'],
+				'line'  => $main_caller['line'],
+				'count' => 1,
+			];
+		}
+
+		$this->set_transient( $stored_queries );
+	}
+
+	/**
+	 * Based on the debug backtrace, try to find the main caller, i.e., the plugin/theme
+	 * that fired the query.
+	 *
+	 * Simple SQL queries generally come from wp-db.php. dbDelta calls come from upgrade.php.
+	 * We are usually interested in the caller immediately before those.
+	 *
+	 * @return array
+	 */
+	protected function find_main_caller() {
+		$debug_backtrace = debug_backtrace(); // phpcs:ignore
+
+		// Remove this plugin references of the backtrace.
+		array_shift( $debug_backtrace );
+		array_shift( $debug_backtrace );
+
+		$main_caller = null;
+
+		$wp_db_found = false;
+		foreach ( $debug_backtrace as $caller ) {
+			$is_wp_db_file = ( false !== strpos( $caller['file'], 'wp-db.php' ) || false !== strpos( $caller['file'], 'upgrade.php' ) );
+			if ( $is_wp_db_file ) {
+				$wp_db_found = true;
+			}
+			if ( ! $wp_db_found || $is_wp_db_file ) {
+				continue;
+			}
+			$main_caller = $caller;
+			break;
+		}
+
+		// If a caller was not found simply get the first item of the backtrace.
+		if ( ! $main_caller ) {
+			$main_caller = array_shift( $debug_backtrace );
+		}
+
+		return $main_caller;
+	}
+
+	/**
+	 * Escape queries to avoid storing sensitive info.
+	 *
+	 * This function takes INSERTs and UPDATEs and replace all parameter values
+	 * between the `'` and `"` chars with `?`
+	 *
+	 * @param string $query The SQL query.
+	 * @return string
+	 */
+	protected function escape_query( $query ) {
+		if ( ! preg_match( '/UPDATE|INSERT/', $query ) ) {
+			return $query;
+		}
+
+		$query = preg_replace( "/[\"'](.*?)[\"']/", '?', $query );
+
+		return $query;
+	}
+
+	/**
+	 * Get the categorized and ordered queries list.
+	 *
+	 * Depending on the query, it may be more or less resource expensive. This function gets all
+	 * queries and return them ordered from the more expensive to the less, and then from the ones
+	 * with higher count to the fewer ones.
+	 *
+	 * @return string
+	 */
+	protected function get_categorized_queries() {
+		$queries_per_date = $this->get_transient();
+		foreach ( $queries_per_date as &$queries_in_day ) {
+			array_walk(
+				$queries_in_day,
+				function( &$query ) {
+					if ( preg_match( '/^\s*(create|alter|truncate|drop)\s/i', $query['query'] ) ) {
+						$query['status'] = self::QUERY_CATEGORIES['medium'];
+
+						if ( $query['count'] > 1 ) {
+							$query['status'] = self::QUERY_CATEGORIES['high'];
+						}
+					} else {
+						$query['status'] = self::QUERY_CATEGORIES['low'];
+					}
+				}
+			);
+			uasort(
+				$queries_in_day,
+				function ( $a, $b ) {
+					if ( $a['status'] === $b['status'] ) {
+						return $a['count'] >= $b['count'] ? -1 : 1;
+					}
+					return $a['status'] <= $b['status'] ? -1 : 1;
+				}
+			);
+		}
+
+		return $queries_per_date;
+	}
+
+	/**
+	 * Get the transient value.
+	 *
+	 * @return array
+	 */
+	protected function get_transient() {
+		if ( TENUP_EXPERIENCE_IS_NETWORK ) {
+			$transient = get_site_transient( self::TRANSIENT_NAME );
+		} else {
+			$transient = get_transient( self::TRANSIENT_NAME );
+		}
+
+		$transient = json_decode( $transient, true );
+
+		if ( ! is_array( $transient ) || JSON_ERROR_NONE !== json_last_error() ) {
+			$transient = [];
+		}
+
+		return $transient;
+	}
+
+	/**
+	 * Set the transient value.
+	 *
+	 * @param array $queries Queries to be stored.
+	 */
+	protected function set_transient( $queries ) {
+		// Order the array, so older entries will be at the start.
+		ksort( $queries );
+
+		// JSON objects will be smaller than PHP serialized() ones.
+		$queries_str = wp_json_encode( $queries );
+
+		while ( mb_strlen( $queries_str ) > self::STORE_MAX_SIZE ) {
+			array_shift( $queries );
+			$queries_str = wp_json_encode( $queries );
+		}
+
+		if ( TENUP_EXPERIENCE_IS_NETWORK ) {
+			set_site_transient( self::TRANSIENT_NAME, $queries_str );
+		} else {
+			set_transient( self::TRANSIENT_NAME, $queries_str );
+		}
+	}
+}
diff --git a/includes/classes/SupportMonitor/Monitor.php b/includes/classes/SupportMonitor/Monitor.php
index 35fb200..7ee8590 100644
--- a/includes/classes/SupportMonitor/Monitor.php
+++ b/includes/classes/SupportMonitor/Monitor.php
@@ -15,12 +15,22 @@
  * Monitor class
  */
 class Monitor extends Singleton {
+	/**
+	 * The DBQueryMonitor instance.
+	 *
+	 * @since x.x
+	 * @var DBQueryMonitor
+	 */
+	protected $db_query_monitor;
+
 	/**
 	 * Setup module
 	 *
 	 * @since 1.7
 	 */
 	public function setup() {
+		$this->db_query_monitor = new DBQueryMonitor();
+		$this->db_query_monitor->setup();
 
 		if ( TENUP_EXPERIENCE_IS_NETWORK ) {
 			add_action( 'wpmu_options', [ $this, 'ms_settings' ] );
@@ -79,6 +89,12 @@ public function ms_save_settings() {
 			$setting['server_url'] = sanitize_text_field( $_POST['tenup_support_monitor_settings']['server_url'] );
 		}
 
+		if ( ! $this->db_query_monitor->is_available() || ! isset( $_POST['tenup_support_monitor_settings']['enable_db_query_monitor'] ) ) {
+			$setting['enable_db_query_monitor'] = 'no';
+		} else {
+			$setting['enable_db_query_monitor'] = sanitize_text_field( $_POST['tenup_support_monitor_settings']['enable_db_query_monitor'] );
+		}
+
 		update_site_option( 'tenup_support_monitor_settings', $setting );
 	}
 
@@ -124,6 +140,14 @@ public function ms_settings() {
 						</td>
 					</tr>
 				<?php endif; ?>
+				<?php if ( $this->db_query_monitor->is_available() ) : ?>
+					<tr>
+						<th scope="row"><?php esc_html_e( 'DB Query Monitor', 'tenup' ); ?></th>
+						<td>
+							<?php $this->enable_db_query_monitor_field(); ?>
+						</td>
+					</tr>
+				<?php endif; ?>
 			</tbody>
 		</table>
 		<?php
@@ -138,10 +162,11 @@ public function ms_settings() {
 	 */
 	public function get_setting( $setting_key = null ) {
 		$defaults = [
-			'enable_support_monitor' => 'no',
-			'api_key'                => '',
-			'server_url'             => 'https://supportmonitor.10up.com',
-			'production_environment' => 'no',
+			'enable_support_monitor'  => 'no',
+			'api_key'                 => '',
+			'server_url'              => 'https://supportmonitor.10up.com',
+			'production_environment'  => 'no',
+			'enable_db_query_monitor' => 'no',
 		];
 
 		$settings = ( TENUP_EXPERIENCE_IS_NETWORK ) ? get_site_option( 'tenup_support_monitor_settings', [] ) : get_option( 'tenup_support_monitor_settings', [] );
@@ -267,6 +292,15 @@ public function register_settings() {
 			);
 		}
 
+		if ( $this->db_query_monitor->is_available() ) {
+			add_settings_field(
+				'enable_db_query_monitor',
+				esc_html__( 'DB Query Monitor', 'tenup' ),
+				[ $this, 'enable_db_query_monitor_field' ],
+				'general',
+				'tenup_support_monitor'
+			);
+		}
 	}
 
 	/**
@@ -335,6 +369,21 @@ public function api_server_field() {
 		<?php
 	}
 
+	/**
+	 * Output production environment field
+	 *
+	 * @since x.x
+	 */
+	public function enable_db_query_monitor_field() {
+		$value = $this->get_setting( 'enable_db_query_monitor' );
+		?>
+		<input name="tenup_support_monitor_settings[enable_db_query_monitor]" <?php checked( 'yes', $value ); ?> type="radio" id="tenup_enable_db_query_monitor_yes" value="yes"> <label for="tenup_enable_db_query_monitor_yes"><?php esc_html_e( 'Yes', 'tenup' ); ?></label><br>
+		<input name="tenup_support_monitor_settings[enable_db_query_monitor]" <?php checked( 'no', $value ); ?> type="radio" id="tenup_enable_db_query_monitor_no" value="no"> <label for="tenup_enable_db_query_monitor_no"><?php esc_html_e( 'No', 'tenup' ); ?></label>
+		<p class="description">
+			<?php esc_html_e( 'Log heavy SQL queries. For performance reasons, only available in non-production environments.', 'tenup' ); ?>
+		</p>
+		<?php
+	}
 
 	/**
 	 * Sends a message async one time
@@ -483,6 +532,14 @@ public function send_daily_report() {
 			);
 		}
 
+		if ( $this->db_query_monitor->is_enabled() ) {
+			$messages[] = $this->format_message(
+				$this->db_query_monitor->get_report(),
+				'notice',
+				'db_queries'
+			);
+		}
+
 		$this->send_request( $messages );
 	}