Alternate to sumif indirect

[kd_too]

Hi All - I have a worksheet where dependent on the data validation value selected, will alter the column to be referenced in a worksheet. This is slowing down my file like crazy when using data validation list. Is there an alternate formula I could try?

SUMIF(INDIRECT(CONCATENATE("'data dump'!",VLOOKUP($A$6,categories!A:C,3,FALSE)),TRUE),CONCATENATE($B9,$A$6,"M`TD"),'data dump'!$M:$M)

THANK YOU