Le jeu. 26 févr. 2015 à 17:08, Tanguy “XRM Toolbox Wizard” Touzard a écrit :

Are Metadata Query Expressions faster that using RetrieveEntityRequest? I mean, you can retrieve less data but the query might be more complicated than just a RetrieveEntity.

Few people responded and some even took a stab at it guessing that it’ll be faster. The last word, however, came from the wizard himself (we took liberty of highlighting important bit):

Finally I had a little time to test so I tested… Way much faster in my case but I’m asking just for two entities (only DisplayName and LogicalName) with all attributes (only LogicalName, DisplayName, AttributeType, OptionSet and Targets). It is just a matter of milliseconds instead of one or two seconds (which obviously retrieve all attributes metadata when you ask for attributes)

To be exhaustive, I should test with a lot of Conditional operator to see if it slows the query (like only Entities of this type with this metadata with this value, and so on)

The developer’s authorative source, a.k.a. SDK, seems to agree with Tanguy.