Power Query Slow When Pulling Data From Exchange

[the_exception]

I'm attempting to pull in Categories and Attributes.LastModifiedTime in via Power Query, but it's going exceedingly slow, taking about an hour and a half to grab the approximately 50,000 e-mails in our Shared Mailbox.

I'm still relatively new to Power Query, so I don't exactly have a baseline.  The below is the code utilized to pull data in, is there something I'm missing?

let
    Source = Exchange.Contents("teammailboxname@company.com"),
    Mail1 = Source{[Name="Mail"]}[Data],
    #"Removed Columns" = Table.RemoveColumns(Mail1,{"Subject", "Sender", "DisplayTo", "DisplayCc", "ToRecipients", "CcRecipients", "BccRecipients", "DateTimeSent", "Importance", "IsRead", "Attachments", "Preview", "Id", "Body"}),
    #"Extracted Values" = Table.TransformColumns(#"Removed Columns", {"Categories", each Text.Combine(List.Transform(_, Text.From), ";"), type text}),
    #"Expanded Attributes" = Table.ExpandRecordColumn(#"Extracted Values", "Attributes", {"LastModifiedTime"}, {"Attributes.LastModifiedTime"})
in
    #"Expanded Attributes"

[v-juanli-msft]

Hi @the_exception 

Do you use Power BI lastest version: September 2019 Update (2.73.5586.561)?

Or do you use power query for excel : version 2.59.5135.201 ? 

You could use Table.Buffer to speed up query.

There are many methods to speed up queries.

Speeding up power query

Performance tip for List.Generate (1): Buffer your tables in Power BI and Power Query

Table.Buffer for cashing intermediate query results or how workaround Unnecessary Queries Issue

Best Regards
Maggie

Community Support Team _ Maggie Li
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