Which opposite of quick?

Both the Elm Creek swim pond and the Maple Grove Community Center pool are frequented by a number of mentally disabled persons. Wading in the water is apparently an exciting and enjoyable activity for many of them. In some ways I think they get to have more fun than anyone, since they retain a child-like enthusiasm for such a simple pleasure even after they are large enough to take advantage of the deeper water. Sometimes they require some extra patience, but usually I find them to make enjoyable patrons since due to their obvious joy.

Today I was in the men's bathroom applying sunscreen before work started, and I had the place to myself. I looked up and saw a man approaching my very slowly. His age was difficult to guess, and his face was disfigured. His crooked mouth gaped open, and one brow was enlarged to the point where he seemed to be limited to sight from the eye on the opposite side. He walked with a limp, his arms stretched out in front of him. I wasn't sure if I should move out of his way or stay still to make navigation easier for him. I decided to stay still, but just as the man neared me, another man, similarly disfigured, entered the room, walking in an identical manner. I was suddenly struck by their similarity to zombies of films. Their lifeless gaze, clumsy gait, and outstretched arms made them dead ringers for the walking dead.

And for just a moment - no more than a single second - I was afraid. I told myself that I was being ridiculous, but my immediate follow-up thought was, maybe that's what all the people in the movies tell themselves. But, of course, my instant of fear was silly, and I was glad it did not prompt me to act. The first man only brushed my shoulder with his arm, and I realized as he passed me that he was merely sticking to the right wall in order to navigate the room. I watched to make sure both men made it to the toilets, and then I departed into the summer sun.