First, when I need to have SketchUp models of hardware like your hinge and door hasp, I prefer to either use the 2D CAD files (McMaster-Carr offers them for many of the items they sell) or I will work from a dimensioned drawing. I create the component with as little detail as I can get away with and still communicate what it is. Since these are not objects that I'll be creating manufacturing drawings for, there's no real benefit in adding lots of detail. The more detail you add the larger the file becomes and the more work your computer has to do to deal with it.
I'd expect that your hinge, for example, doesn't really need a pin. Maybe the hasp doesn't need the hinge portion on the back.
Now, before extensions, the first thing I do is look closely at the geometry. Turning on Hidden Geometry helps because it shows stuff like all those softened edges I showed in the screen shot. I also work with the Face Style set to Monochrome so I can identify and fix reversed faces.
Then as far as extensions go, there's Thom Thom's CleanUp3 and Solid Inspector2. There's also Fixit. Look in the Sketchucation Plugin Store.
FWIW, I often hear people say they don't want to spend the time creating components but they usually spend much more time fixing up components made by others to make them usable or waiting for their computer to complete some task due to the obese components someone else made. I'd rather put in a few minutes up front and make a good component than waste the time fixing what somone else did or dealing with objects imported from other software.
FWIW, if you use 2D .dxf or .dwg files in SketchUp, use them as references but draw your own geometry.
