Cpu Bursts whenever i upload images on the website. I upload 17 or 18 bulk images and cpu capacity bursts and website gets down for half an hour to 2 hours.

Hello, It appears that you are running out of resources on that very small instance.

You have two options, bump up to a larger instance that can handle the load, or figure out if there's anything you can eliminate to reduce the resources you are using.

The easiest thing to do is option number one. Take a snapshot of your instance and then restore it to a "bigger" Lightsail instance type and see if that keeps you out of the "CPU burstable zone".

You can monitor the burst capacity by following the steps in this blog: https://aws.amazon.com/blogs/compute/proactively-monitoring-system-performance-on-amazon-lightsail-instances/ -- [1]

Wordpress is pretty bad at multiple image upload - it's using lots of RAM doing this and will lock up the instance if multiple uploads are done in parallel because of the memory exhaustion.

You'll need to see how to tune up its memory usage, there are many things that can be attempted depending on your case.