Java app servers with high request rates suffered this problem, leading to throttling of SSL session creation and thus reducing effective requests per second on the server.

I doubled throughput on two different projects by 'fixing' the /dev/random-/dev/urandom problem.

But writing your own can be worse. Stumbled onto a substantial CSRNG bug on an embedded system than was ignoring most of the seed data due to a premature optimization in the ingestion code. Even after that the people who wrote the glue code wanted to do their own entropy mixing. Lesson not learned, at all.