As a SSRS consultant, we’re often asked how to speed up reports. While there are many ways to do it, I would make this the top one: Put parameters in the query, not in the dataset filter, if at all possible.
Filtering is not your friend. Repeat after me: Put your parameters in your query, not in your filter.
To show you why, let’s look at two reports: one called Parameter in Filter, the other Parameter in Query. Both reports are identical except for one thing—in one report I use a filter on the dataset and in the other I use a filter in the query itself.