Without boots and a sword, many runners will elect to diagonal all the way to the left rail after hitting the floor switch, but it is possible to be up to 4 pixels away from the left rail (12E4) while still avoiding the leftmost popo, which can save a few frames on movement.
An alternative (and equally fast) strategy is to use an item such as the hookshot, boomerang, or bow to stun or kill the leftmost popo. However, using a sword slash or a slower item (such as the hammer) instead will end up losing you time.
If you have the boots but no sword, it's not possible to take the simple straight dash through the room, so using one of the above strats is recommended instead. A capedash can technically save you close to a second of time over walking, but is unlikely to be viable for two reasons: