Power BI Dashboard Optimization & Upgrades

I have a well-used financial reporting dashboard in Power BI that has become noticeably sluggish. Refresh cycles crawl, and once the data is finally loaded the visuals hesitate when users slice, drill, or filter... (Budget: $750 - $1500 USD, Jobs: Business Intelligence, C# Programming, Data Analysis, Data Visualization, Database Programming, Microsoft Access, Power BI, SQL)