Setting the governor to "performance" should mean the processor runs at the maximum frequency set in
config.txt, or the default if there isn't one. Note that this is generally pointless except in unusual contexts, since when required gearing up to a higher frequency happens much faster than is humanly perceivable.
I have read that using a raspberry pi B+ due to the more stable power supply, I do not have to worry about corrupt SD cards. Is this true?
It's possible that to the extent that the earlier models might have been prone to corrupt SD cards due to power issues, the newer models might be better. However, to my knowledge there has never been an admission of such an issue with any of them (discounting defective units, which any piece of electronics can be defective), and I am confident in saying that the vast majority of Pi users have never had any serious issues with SD corruption. However people do not post online that their computer worked fine today, so if you go by reports online, it may appear that there is a significant issue when there is not.
Our reports of such here did seem to peak during a period of time a few years ago before the newer models became predominant, but there may be another explanation for that -- in addition to the user base in general smartening up to the most common cause, which is yanking the cord when the system is very busy, particularly with I/O to the card. If you have to yank the cord for some reason, give it a bit of time to idle if possible and wait until the green ACT light is not blinking furiously. There is no form of power regulation that can prevent this issue on the pi or any other computer, because it really is not the hardware that is "to blame". It's a logical chicken-and-egg type complication of what complex software may be doing when it is arbitrarily interrupted.
You can pay $5000 for a desktop and it will also be subject to a risk of corrupting data on permanent storage if you yank the cord from the wall without shutting it down properly. Electronic devices with writable storage which can be shut down via a button actually go through a process which may take several seconds to help ensure the integrity of stored data. The Pi does not have such a button, but you can implement one or buy such from various third parties.