Problem Details:
the replay speed still 1.0x when it should be 0.5x or 2.0x (works with map with audioleadin)

How to Replicate?

1. open any kind of replay/watch gameplay
2. after the beatmap is loaded, quickly press F
3. voile, the speed remains 1.0x

(kinda hard to tell)

osu! version: 20130910 (latest)

Replicated.
You people and your ninja reflexes. You can fix that easily by changing speeds again.

Yup, I'll let this confirmed since it happens to me too:
1. Open replay
2. While you have loading circle, press F rapidly
3. Playback sprite changes, without speed actually changing.

Rather low priority.