DotSpatial loads all features from a shapefile into RAM when adding it to the map, there is a limit to the size of shapefile that can be viewed. We need a file-based approach that still has good performance but does not have a large memory footprint for large shapefiles.
 
Some of the low-level pieces for file-based access to large shapefiles are done (classes implementing the IShapeSource and IFeatureSource interfaces). However, we still need to implement Map Layers that work and play well with the rest of DotSpatial while using a file-based approach.