Recently, I am experiencing slowness with the power bi desktop application.
I believe it is due to the data sources and relationships I have.
I have about 30 data sources and around 40 relationships in my PBIX file. Working on 10 pages/tabs report(s).
Anything can be done? Best practices?
It is almost impposible to work like that.
First of all, use the latest version of Power BI.
Please refer to these guidance documents. power-bi/power-bi-reports-performance and power-bi/visuals/power-bi-visualization-best-practices.