He slowed his pace so his companion could catch up.
Tips
usage
放缓 is most often used about pace, rhythm, or growth rate - 放缓脚步 (pace), 放缓节奏 (rhythm), 放缓增速 (growth rate), 放缓步伐 (stride). Compare 减速 ('reduce speed', mostly physical motion) and 放慢 ('slow down', overlapping but slightly more concrete).
