Author here. Yes, the search bar is nice already, and the performance is good enough for most use cases. Fun fact, javadoc's search is O(n), Docland uses binary search so it's O(log2n). That's why the search bar in the official java.base documentation is noticeably laggy.

The real benefit of customizing search is custom ranking and filtering logic. Docland sorts the search results by relevance (matching prefix length and casing) and dedupes overloads. In my (possibly biased) opinion it's easier to use.