PHP PDF generation becomes slow when creating large documents

I am working on a PHP-based worksheet generation system and recently ran into a performance problem. The application generates printable PDF files based on user-selected options. The workflow is: User selects options ↓ Server generates data ↓ PHP creates PDF ↓ User downloads the file The problem is that the generation time increases significantly when the document contains many items. For example: 100+ exercises multiple pages answer pages custom layouts Current implementation The frontend sends a POST request to the PDF generation endpoint: $result = http_post( "https://www.wativate.com/?api/pdf/generate", [ "operation" => "addition", "questions" => 100, "include_answers" => true ] ); The server receives the parameters and starts generating the PDF. A simplified version: function generateWorksheetPDF($options) { $problems = generateProblems( $options['questions'] ); $html = renderHTML($problems);