What do you think of when I say the word, acceleration? For those who make cold process soap, this word is equivalent to doom or perhaps panic. Even though your fragrance oil may smell absolutely heavenly, it's behavior in CP may be quite the opposite. This is why you must check, check, check-- do your research first and make sure you are prepared to deal with a troublemaker scent. I try not to completely avoid using fragrances that act up; they smell too good!
Here's an example: Non-Discoloring Vanilla. Yes, it won't go brown, but read Bramble Berry's warning label: "This fragrance can be tricky in some cold process soap recipes. It may accelerate trace and/or rice so soap carefully." This means stir in your scent at the very end before pouring and try not to make any time-sensitive detailed swirls. I was feeling daring and tried a swirl to see what would happen.
The soap thickened and got very hot right away. When this happens, take a deep breath and try not too get too discouraged. Get your soap in the mold asap! Notice the bars are a bit rustic and uneven-- they almost look hot processed.
With a little trimming to even out the top, the bars and swirl actually came out great!