One thing that frustrates me with estimating performance on AWS is that I have to dramatically estimate down from the performance of my dev laptop (M2 MBP). I've noticed performance tradeoffs around 15x slower when deployed to AWS. I realize that's a anecdotal number, but this is a fairly consistent trend I've seen at different companies running on cloud hosting services. One of the biggest performance hits is latency between servers. If you're server is making hundreds or thousands of db queries per second, you're going to feel that pain on the cloud more even if your cloud db server CPU is relatively bored. It is network latency. I look at the costs of AWS and it is easy to spend >$100,000 month.
I have ran services on bare metal, and VPSs, and I always got far better performance than I can get from AWS or GCP for a small fraction of the cost. To me "cloud" means vendor lock-in, terrible performance, and wild costs.
People do not realize for that fancy infinite storage scaling, that it means that AWS etc run network based storage. And that, like on a DB, can be a 10x performance hit.
I have ran services on bare metal, and VPSs, and I always got far better performance than I can get from AWS or GCP for a small fraction of the cost. To me "cloud" means vendor lock-in, terrible performance, and wild costs.