Database Caching Mixed Results

Yii 2.0 General Discussions
1

I’m trying to see if an application I have can be tuned any better. I’ve spent a lot of time fine tuning database indexes and the improvements have been quite noticeable, which is great.

I then started reading https://www.yiiframework.com/doc/guide/2.0/en/tutorial-performance-tuning#enable-schema-caching regarding enabling caching, so I implemented the settings, but I’m not seeing much improvement, even some slowdowns.

I add the settings to my common\main-local.php

<?php
return [
    'components' => [
        // caching - also see db component for settings
        'cache' => [
            'class' => 'yii\caching\FileCache',
        ],
        'db' => [
            'class' => 'yii\db\Connection',
            'dsn' => 'mysql:host=localhost;dbname=xxxx',
            'username' => 'xxxx',
            'password' => 'xxxx',
            'charset' => 'utf8',
            // caching - 3 next lines
            'enableSchemaCache' => true,
            'schemaCacheDuration' => 43200,  // 12 hours
            'schemaCache' => 'cache',
        ],
    ],
];

Am I doing something wrong?
Just looking for any pointers?