Comment by torginus
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.
Lambda in my eyes is super useful for isolating a security context, such that you can give elevated privileges to a less protected place via permission to execute the lambda; isolating something dangerous or secret from the less secure place