As part of the search team, I worked on a project where we deliberately rewrote the whole product search engine in Python and Cython, including our own algorithms manipulating documents for deletion, low latency reindexing after edits, and more.
We did this because SOLR was too slow and the process of defining custom sort orders (for example, new sort orders defined by machine learning ranking algorithms, and needing to be A/B tested regularly) was awful and performance in SOLR was poor.
It was a really fun project. One of the slogans for our group at the time was “rewriting search in Python for speed.”
The ultimate system we deployed was insanely fast. I doubt you could have made it faster even writing the entire thing directly in C or C++. It became a reference project in the company to help avoid various flavors of arrogant dismissal of Python as a backend service language for performance critical systems.