In Terry Pratchett's Discworld novels there are trolls made from rock with silicon-based brains. They are usually also dumb as rocks – until the temperature gets cold enough, then they suddenly become hyper-intelligent.
Ignoring creative liberties, it is assumed silicone based life forms would need high temps to thrive. Is quite possible that they would immediately die if exposed to human temps. Possibly these high temps would result in very fast computational skills.
Is interesting though. The speed at which you think is not entirely related to intelligence. If you created a computer the size of the solar system, it would be far far far more intelligent than an individual human. But because information would take hours to traverse across different regions of that brain, conversations and answers to questions might be incredible slow to come. We actually already take this into consideration when designing computers. The physical length memory is from the CPU is now critical.
"Today a young man on acid realized that all matter is merely energy condensed to a slow vibration, that we are all one consciousness experiencing itself subjectively, there is no such thing as death, life is only a dream, and we are the imagination of ourselves. Anyway, heres Tom with the Weather." - Bill Hicks