By poor performance, I assume you mean IO? AWS Elasticsearch has supported i3 instance type (nvme on-instance storage) for well over a year now [0]. Additionally, you could enable slow-logs to catch perf issues yourself [1]
> very slow to make cluster changes
Scale-out and access-policy changes happen in-place now and so happen much faster than they used to be.
> launch new clusters
In my experience, it depends on the cluster size, but usually, I see cluster being up in 20m. That's nice given that it sets up pretty much everything (spin up instances, apply access policies, run health checks, enable cloudwatch monitoring, snapshots, create route53 records, integrate with cognito, enc-at-rest via KMS, spin up load balancers, setup vpc resources etc) on my behalf.
[0] https://docs.aws.amazon.com/elasticsearch-service/latest/dev...
[1] https://aws.amazon.com/blogs/database/analyzing-amazon-elast...