I confirm that with version 188.8.131.529 the reports are rendered in parallel, with a configurable count of threads. Is it possible that the REST Service is configured to use a single thread, for example, if it is running on a virtual machine?
You may attach a Trace Listener to the service. Our code writes relevant information in the trace log that may point us to the core of the issue.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items