[Twirrim]

A team I was on in the past had a well known bottleneck for performance on the most performance critical component. It was one that couldn't possibly be avoided or minimised. It was one called with high frequency, and wall clock wise, didn't take too long.

"JNI is slow", being the conventional wisdom, and knowing just how frequent the calls would be, people had ignored it as an option.

Randomly one of the devs who was most bothered by the bottleneck, had an hour spare and threw the conventional wisdom out the window and dropped in JNI calls to an standard (highly optimised) library and re-benchmarked. 40% performance boost. Further experiments found that "JNI is slow" isn't as true as conventional wisdom quite had it.