I used to have MM set to store 3 months worth of sales few years ago but it made loading so unbearably slow (I presume not because of the physical size of data but the processing power required to go through tens of thousands of entries being crunched on one sad CPU core) I had to go back to the usual 30 days.
There's also this indexing thing I am vaguely aware of but I never tried that and don't remember what it does.
But it looks like my assumption was correct and I have to make a choice (which I already did it seems) of convenience vs performance
I wish the game had a little more modern engine.