How to improve performance?

t-atgeor Depending on the problem you're facing it can be looked at to improve performance within your report. In general I would suggest,

1 Make sure data you publish to report is only what you require ie for a sales report you only publish data for past 2-3 years if that is all going to be analysed instead using whole table.

2. Explore possibility of DirectQuery which in some cases can be better solution than Import.

3. In my experience I've realised using Page / Report level filters have better performance than using visual-level filters. 

4. Try avoiding too complex measures / calculated columns instead do them at the data source level.