A person’s intelligence should not be measured by how quickly they speak your language.

Speed in a second language measures practice, not thinking. Someone assembling a sentence carefully may be holding a more complicated idea than the fluent speaker beside them, but hesitation sounds like slowness and the ear judges before the mind can object. That judgement says more about the listener than about the person speaking. Language is a surface, and it is a poor gauge of what is underneath.

Wait through the pause instead of finishing the sentence. Ask again slowly rather than simplifying the idea. Notice whether you change how you talk to someone with an accent, and adjust your assumptions rather than your volume.