Hot corners should ideally take no more than a quick flick to activate. Which is why I tend to recommend either a Terminal hack, or a 3rd party utility that does the Terminal hack for you, or a 3rd party utility with a range of mouse contril options, including control over tracking.
For a faster mousing experience:
Developer is already working on Magic Mouse support. This guy is fast. I recommend this.
Or . . .
Not bad, but I prefer USB Overdrive. Steermouse's developer seems to take a bit more time getting on the ball with major updates.
Both utilities offer a huge range of customizing options.
If you have any of these utilities you can (in most cases) forego 3rd party manufacturers' own drivers (most of which I can't stand), such as Logitech Control Centre.