Unfortunately it is not possible to override draw method on the information layer. But actually it is not necessary. The things you've described can be implemented without it. For example, using DynamicLayer you can show only shapes which are in the viewing area. You also can optimize your shapes by removing unnecessary points before passing them to the dynamic layer.
If you use a shape-file, then you might try to simplify it for improve the performance with this online tool:
I have attached a sample solution which uses the DynamicLayer with map shapes.
I hope it helps.
the Telerik team