add some "translators" comments.

classes/autoptimizeConfig.php

@@ -365,7 +365,9 @@ public function show_config()
 <?php
 $_rapidload_link = 'https://misc.optimizingmatters.com/partners/?from=csssettings&partner=rapidload';
 ?>
-<td><?php echo sprintf( __( 'If Google Pagespeed Insights detects unused CSS, consider using %s to <strong>reduce your site\'s CSS size to up to 90&#37;</strong>, resulting in a slimmer, faster site!', 'autoptimize' ), '<a href="' . $_rapidload_link . '" target="_blank">the premium Rapidload service</a>' ); ?></td>
+<td><?php 
+// translators: the variable contains a link to rapidload.
+echo sprintf( __( 'If Google Pagespeed Insights detects unused CSS, consider using %s to <strong>reduce your site\'s CSS size to up to 90&#37;</strong>, resulting in a slimmer, faster site!', 'autoptimize' ), '<a href="' . $_rapidload_link . '" target="_blank">the premium Rapidload service</a>' ); ?></td>
 </tr>
 <?php } ?>
 </table>

classes/autoptimizeCriticalCSSBase.php

@@ -359,6 +359,7 @@ public function ao_ccss_interval( $schedules ) {
         // Attach interval to schedule.
         $schedules['ao_ccss'] = array(
             'interval' => $intsec,
+            // translators: the variable contains a string describing the insterval.
             'display'  => sprintf( __( 'Every %s (Autoptimize Crit. CSS)', 'autoptimize' ), $inttxt ),
         );
         return $schedules;

classes/autoptimizeMain.php

@@ -757,6 +757,7 @@ public static function notice_cache_unavailable()
     public static function notice_installed()
     {
         echo '<div class="updated"><p>';
+        // translators: the variables contain opening and closing <a> tags to link to the settings page.
         printf( esc_html__( 'Thank you for installing and activating Autoptimize. Your site is being optimized immediately, please test the frontend to ensure everything still works as expected. If needed you can change JavaScript or CSS optimization settings under %1$sSettings -> Autoptimize%2$s .', 'autoptimize' ), '<a href="options-general.php?page=autoptimize">', '</a>' );
         echo '</p></div>';
     }