[Resolved] Syncing custom fields performance issues

	function copy_custom_fields( $post_id_from, $post_id_to ) {
		$custom_fields_to_copy = $this->get_custom_fields_translation_settings( WPML_COPY_CUSTOM_FIELD );
		$custom_fields_from    = get_post_meta( $post_id_from );
		$custom_fields_to      = get_post_meta( $post_id_to );

		foreach ( $custom_fields_to_copy as $meta_key ) {
			if ( array_key_exists( $meta_key, $custom_fields_from ) ) {
				$meta_from = isset( $custom_fields_from[ $meta_key ] ) ? $custom_fields_from[ $meta_key ] : [];
				$meta_to   = isset( $custom_fields_to[ $meta_key ] ) ? $custom_fields_to[ $meta_key ] : [];

				if ( $meta_from || $meta_to ) {
					$this->sync_custom_field( $post_id_from, $post_id_to, $meta_key );
				}
			}
		}

		$sync_deleted_fields = false;
		/**
		 * This filter hook determines whether we should sync deleted custom
		 * fields to translations.
		 *
		 * @since 4.4.9
		 *
		 * @param bool $sync_deleted_fields True if we should sync deleted custom fields (the default is false).
		 *
		 * @return bool
		 */
		if ( apply_filters( 'wpml_sync_deleted_custom_fields', $sync_deleted_fields ) && $custom_fields_from && $custom_fields_to ) {
			$if_deleted_in_source_and_still_in_target = Logic::allPass(
				[
					Obj::prop( Fns::__, $custom_fields_to ),
					pipe( Obj::prop( Fns::__, $custom_fields_from ), Logic::not() ),
				]
			);

			wpml_collect( $this->get_custom_fields_translation_settings( WPML_TRANSLATE_CUSTOM_FIELD ) )
				->filter( $if_deleted_in_source_and_still_in_target )
				->map(
					function ( $meta_key ) use ( $post_id_from, $post_id_to ) {
						$this->sync_custom_field( $post_id_from, $post_id_to, $meta_key );
					}
				);
		}

	}

	public function copy( $post_id ) {
		$custom_fields_to_copy = $this->sitepress->get_custom_fields_translation_settings( WPML_COPY_ONCE_CUSTOM_FIELD );
		if ( empty( $custom_fields_to_copy ) ) {
			return;
		}

		$source_element_id = $this->wpml_post_translation->get_original_element( $post_id );
		$custom_fields     = get_post_meta( $post_id );

		foreach ( $custom_fields_to_copy as $meta_key ) {
			if ( array_key_exists( $meta_key, $custom_fields ) ) {
				$values = isset( $custom_fields[ $meta_key ] )
				          && ! empty( $custom_fields[ $meta_key ] )
					? [ $custom_fields[ $meta_key ] ]
					: [];

				/**
				 * Custom fields values for given post obtained directly from database
				 *
				 * @param array<mixed> $values Custom fields values as they are in the database
				 * @param array<int|string> $args {
				 *
				 * @type int $post_id ID of post associated with custom field
				 * @type string $meta_key custom fields meta key
				 * @type int $custom_fields_translation field translation option
				 *
				 * }
				 * @since 4.1
				 *
				 */
				$values = apply_filters(
					'wpml_custom_field_values',
					$values,
					[
						'post_id'                   => $post_id,
						'meta_key'                  => $meta_key,
						'custom_fields_translation' => WPML_COPY_ONCE_CUSTOM_FIELD,
					]
				);

				if ( empty( $values ) && $source_element_id ) {
					$this->sitepress->sync_custom_field( $source_element_id, $post_id, $meta_key );
				}
			}
		}
	}