PhotoDemon provides a highly optimized motion blur tool. (In our testing, it is significantly faster than the motion blur tools in GIMP and Paint.NET.) Angle and distance can be set independently, and a symmetrical option is available if you want to blur the image equally in both directions (e.g +/- 45 degrees in the sample image).
Like all PhotoDemon tools, a dedicated command bar allows you to save and load custom presets, randomize parameters, and reset to default values. Last-used settings are automatically saved and restored, and all changes provide a real-time preview (no click or mouse button release required).