The phrase 'fast as usual' is a correct and usable part of a sentence in written English.
For example, you could use it in a sentence like, "I finished my assignments fast as usual."
"So no wonder her brain wasn't working as fast as usual.
In the film, Summerall seems more himself than Madden, whose hyperactive style of analysis seems half as fast as usual.
We heard the unmistakable bass line to the White Stripes Seven Nation Armymy," but the song was playing noticeably slowly — perhaps two-thirds as fast as usual.
"I've run relatively small Python applications nearly thrice as fast as usual speeds, but for more realistically-sized applications, I'm yet to achieve such significant increases". He says that the pressure to deliver improvements relating to hardware is even greater.
Relatively complete sensory deprivation (such as may be experienced, for example, by persons undergoing prolonged stays in experimental isolation chambers) compresses the experience of time to the point that short or long intervals (from about a minute to a day) seem to pass about twice as fast as usual.
