You can, if you're willing to invest the time, improve EF's performance by using As No Tracking and writing more complex LINQ and lambda expressions than Dapper-to-EF LINQ examples I've seen.
There is no real equivalent to EF's navigation properties so, if you want to retrieve data from multiple tables, you'll need to write your own SQL Join statement.
When trying to decide between using the Entity Framework and Dapper as an ORM, what are the advantages and disadvantages of Entity Framework and Dapper?
The downside is that you'll have to assemble a Dapper toolkit by picking and choosing among Dapper extensions with the real possibility that, once you add enough functionality, you'll have given up Dapper's edge in performance compared to EF.
Using Dapper requires writing a little more code than EF LINQ (provided, of course, you ignore EF's upfront work in creating the context object). The simplest way to use Dapper is to pass an SQL statement or stored procedure name to Dapper's Query extension method.
If you want to submit multiple SQL statements at once, you can use Dapper's Query Multiple method.