I'd argue the real issue with Terraform is that workspace orchestration is necessary in the first place. If they addressed the performance issues with large workspaces, then we wouldn't need to split up workspaces and Terraform could just orchestrate changes naturally.

The performance issues in large workspaces are due to needing to refresh status on all the resources in the large workspace before coming up with a plan. Actual apply time is either negligible or the inherently long amount of time it's supposed to take.

You split the workspace into smaller workspaces precisely to tell Terraform that you haven't made any changes to the networking layer, so don't bother trying to refresh the status of the networking layer to see if any changes are needed, it's not relevant when you're trying to scale up your Kubernetes cluster or whatever.