S: (adj) fleet, swift (moving very fast) "fleet of foot"; "the fleet scurrying of squirrels"; "a swift current"; "swift flight of an arrow"; "a swift runner"
W: (adj) slow [Indirect via fast] (not moving quickly; taking a comparatively long time) "a slow walker"; "the slow lane of traffic"; "her steps were slow"; "he was slow in reacting to the news"; "slow but steady growth"