There could be a couple reasons as to why you could be experiencing such high levels of inconsistency, such as insufficient ram, network congestion, CPU size, etc
Howver, you can troubleshoot this by using cloudwatch
1- Check the CloudWatch metrics for your instance, including CPU usage, network traffic, and disk I/O. This can help you identify if any of these resources are causing the issue.
2- Try resizing your instance to a larger size to see if that improves performance.
3- Check the logs of your applications and services to see if there are any errors or performance issues that are causing the slow performance.
4- Check the AWS Service Health Dashboard to see if there are any issues with the network or infrastructure in the region.
5- Contact AWS Support for further assistance if you are unable to resolve the issue.