t2.micro becomes slower and slower

Hello there

Please note that t2.micro instances have 1 vCPU and baseline performance is 10% of this vCPU. So if workload burst more than 10% CPU usage, it will start consuming burst credits. Once this burst credits becomes 0, the CPU usage will be throttled at 10% baseline. This will be seen as slowness.

Please refer https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/burstable-credits-baseline-concepts.html for more information.

You can choose higher instance type or move to t2 unlimited option

https://aws.amazon.com/blogs/aws/new-t2-unlimited-going-beyond-the-burst-with-high-performance/