Just to nullify the original implication in this thread, when Oswald got out of Frazier's car he did not rush off while Buell charged the battery. He waited for a time, then moved when Frazier alighted. It was Frazier who dawdled along watching trains and eventually finished about 50 feet behind. This is about 10 seconds.
Over a 5 minute walk this means that Oswald would have walked about 3% faster than Frazier.