---
description: 
globs: 
alwaysApply: false
---
# Moodle Performance Optimization

## Purpose
Ensure PHP code follows Moodle performance best practices for optimal execution speed and resource usage.

## Instructions
When writing PHP code for Moodle, implement these performance optimizations:

1. **Database Queries**: Minimize database calls, use bulk operations when possible
2. **Caching**: Use Moodle's caching API (`cache::make()`) for expensive operations
3. **Memory Management**: Avoid loading large datasets into memory, use pagination
4. **File Operations**: Use Moodle's file API, avoid direct file system access
5. **Session Handling**: Minimize session writes, use `$SESSION` sparingly
6. **Output Buffering**: Use `ob_start()` and `ob_end_flush()` for large outputs
7. **Error Logging**: Use `debugging()` instead of `error_log()` in production
8. **Plugin Loading**: Lazy load plugins and dependencies when possible

## Examples

```php
<?php
// File: ./includes/performance_example.php

/**
 * Example of performance-optimized code
 */
function get_optimized_course_data($courseids) {
    global $DB;
    
    // Use caching for expensive operations
    $cache = cache::make('core', 'course_data');
    $cachekey = 'course_data_' . md5(serialize($courseids));
    
    $cacheddata = $cache->get($cachekey);
    if ($cacheddata !== false) {
        return $cacheddata;
    }
    
    // Bulk database query instead of multiple queries
    list($insql, $params) = $DB->get_in_or_equal($courseids, SQL_PARAMS_NAMED);
    $sql = "SELECT c.*, COUNT(e.userid) as enrolled_users
            FROM {course} c
            LEFT JOIN {enrol} e ON c.id = e.courseid
            WHERE c.id $insql
            GROUP BY c.id";
    
    $courses = $DB->get_records_sql($sql, $params);
    
    // Cache the result for 5 minutes
    $cache->set($cachekey, $courses, 300);
    
    return $courses;
}

/**
 * Efficient file handling
 */
function process_files_efficiently($contextid) {
    $fs = get_file_storage();
    
    // Use file iterator for large file sets
    $files = $fs->get_area_files($contextid, 'mod_assign', 'submission');
    
    foreach ($files as $file) {
        if ($file->is_directory()) {
            continue;
        }
        
        // Process file without loading entire content into memory
        $content = $file->get_content();
        // Process content in chunks if large
    }
}
```

## Exceptions
- Development environments may use different performance settings
- Debugging may require bypassing some optimizations