Sony has now confirmd that the PSP can not use its full CPU power while WiFi is enabled, which results in games with network gameplay not being able to utilize the full 333MHz clock speed.

Quote:
"The recent firmware upgrade (3.50) that removed the restriction on the PSP's CPU speed enables developers to utilize speeds either lower or higher than the default 222MHz, up to the full 333MHz clock speed. The article is correct that increased CPU speed cannot be used with the PSP's wireless feature," Karraker said. "SCEA is working closely with the development community to take full advantage of this new functionality where appropriate for their titles."

As Beyond3D points out, this limitation has some implications for PSP developers: "Game titles with network play could effectively be either limited to using 222MHz only during single player mode, or to using a downgraded engine and assets for multiplayer mode, which could complicate the development process."