Create efficient "development mode" for Query Editor query refreshes
As of August 2019, development of queries with large result sets is painfully slow. It appears this has been a problem for several years. Building power queries is on the critical path and a pre-requisite to data modeling. There also seem to be some defects related to the Power Query implementation in PBI Desktop. Anecdotally, sometimes by cancelling and restarting refreshes, or performing an overlay install of PBI can help queries once "frozen" during a refresh cycle magically return results instantly.
Ideas to remedy Power Query performance:
1) Cache the entirety of "base" queries from which others are "referenced".
2) Build test cases for resultsets in the 10s of millions.
3) Allow developers to specify query refresh order.
4) Debug parallel loading and background refresh performance inconsistencies.
5) Allow the user to cache all power query results in memory.