Use the FeatureHolder transformer in front of the Clippee port to hold all features entering that way until all Clippers are read into the Clipper transformer.

But the advantage of this approach in the Clipper might not exceed the disadvantage of holding the features in the FeatureHolder. You will need to do a performance test.

I agree completely. I think the better option would be to create a separate reader just for the clipper geometries, then make sure that reader is moved at the top of the navigator.