I think it's highly dependant on the size of the source string and the size of the match string/regex after trying a couple more examples that are based on yours.

However, I do see a trend that #include? does tend to yield slightly better speeds on average (not all cases).  What all that said, we're talking about tolerances of less than a micro-second in normal operation of this test (1 operation vs. 10 million), but I'll move the simple ones over to #include?