You can see if the cost-based optimizer has been used in the generation of a query plan by looking at the query's execution trace. When it is used, a "Cost Optimization" header appears under the execution node. For more information, check this out:
When working with cached views, it is important to know that the statistics are generated using the original data source itself, not the cached version. Keep that in mind if the cache mode is different from full.
Hope this helps!