Improve Codeigniter back-end functionality

Hello, I have a back-end for my app which used PHP Codeigniter framework there is currently two problem: 1) In Dashboard section it will display a list of absent student for the current date which is the default behavior for it so some time if the list is too long the backend will display some errors which cause it not display after login so in this case i can't use the backend at all. I need to ether enable pagination to display only 20 students in each page ( which preferable ) or remove the default behavior and use the option i have in the page. 2) In Class Absent section I can choice the date and class to display/print attendance for a specific class which work fine but there is another option "All Classes" which let me print all classes at once currently not working properly because of A communication error occurred: "Operation timed out". So i need help to fix those also to improve the backend functionality work if possible. Notes: My max budget will be $100 only