One of the easiest hack to reduce your AWS bills is to migrate from x86 to arm64 CPU. Performance difference is negligible, and cost can be upto 50% lower for arm machines. This is for both RDS and general compute (EC2, ECS). Would recommend to all.

I'd say the best price/performance hack on AWS if you don't need web scale is just put your stuff on a tiny EC2 instance, like a t3.micro - it'll be likely faster and more flexible than lambda with much more predictable performance.

You can scale up by changing out to a bigger instance - it's surprising how far you can get with this strategy.

How is the performance difference negligible? In my experience, for the same generation of hardware, ARM64 performance is better than the AMD64 one.

AFAIK ARM64 is around 20% cheaper, not sure where you got the 50%.