Improving search performance using saved search or summary index ???

Hi All, I am running a search which shows the total_used_space (storage used) of an application for last 30 days. Below is the query for the same, but it takes some 40 to 45 seconds to load the panel. I want to improve the performance of this search, so that the panel loads faster. I tried creating a saved search and use that search in the panel, but still it is running very slow. Below is the search: index=app sourcetype="app:users" | dedup user| stats sum(space_used) as total_space | eval total_space=round(total_space/1024/1024/1024/1024,2)."TB" Please suggest on how can I create a summary index for this, as I think summary index would improve the performance for the same. Please help resolve this issue ? Thanks PG