Prevent entity framework model from rebuilding every time

I've got an entity framework based data layer which is in a separate assembly. In the same solution I've got a business assembly, as ASP.Net MVC application and some unit test assemblies. The EF model is quite large and takes around 20 seconds to build. My problem is it's getting rebuilt every time a build is required. If I change one line in a unit test I have to wait 20+ seconds for the build to complete. Anyone know of any tricks to prevent the EF model triggering rebuilds (I don't want to 开发者_如何转开发unload the assembly from the solution)?

In the properties of the solution, I believe you can specify what assemblies get built for the solution. Right click on the solution and select "Properties". Select the Configuration Properties. In the right pane you can select what items get built. Hope this helps.