Category Combination Purchase

Hi, Anonymous 

I don't think the month-wise slicer has a significant impact on the timing of generating the results. The time is too long mainly because you have too much data, I guess the connection mode of your model data is import? Changing the data connection mode to direct query or live connection may help.

There is a month-wise slicer that provides additional calculation logic. If you don't need it, just delete the judgment statement about the month-wise slicer in the above measures.
Like:

_I_Item = 
var _I_Item=SUMMARIZE(FILTER(ALL('Table'),'Table'[CustomerId]=MAX('Table'[CustomerId])),[Item ])
var _I_Item_Month=SUMMARIZE(FILTER(ALL('Table'),'Table'[Month]=MAX('Table'[Month])&&'Table'[CustomerId]=MAX('Table'[CustomerId])),[Item ])

var _if_Month=
    CONCATENATEX(_I_Item_Month,[Item ],","),CONCATENATEX(_I_Item,[Item ],",")
return _if_Month

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Best Regards,
Community Support Team _ Zeon Zheng

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