Tree-sitter is too slow for large c++ project such as Unreal Engine

[EnoroF]

For large-scale projects like C++ projects in Unreal Engine, the efficiency of Tree-sitter is notably low. It currently spends an excessive amount of time during the index building process.

[therecluse26]

@EnoroF Thanks for the report. Can you share the exact command, Reflex version, hardware, rfx stats, and the indexed file count/bytes?

One clarification: Reflex should not be running Tree-sitter across the entire repo during normal full-text indexing. The documented architecture is trigram indexing at index time, with Tree-sitter used for symbol/AST/reference-style queries after the trigram index narrows candidates. So if plain rfx index is spending most of its time in Tree-sitter, that may be a bug or a code path we need to inspect.

That said, Unreal-sized C++ projects are a worst-case workload. The first build of a local code-aware index is expected to be slower than a one-off text scan, but the value is that subsequent queries and incremental refreshes should be fast. Reflex is intentionally trading some complexity for symbol-aware search, dependency analysis, references, and agent-friendly context. If someone only needs raw text search, a grep-like indexed search tool may be a better fit, but it will not provide the same code-level semantics.

Please include timings for: first rfx index, no-change rfx index, a small edit followed by rfx index or rfx watch, and the specific symbol query that feels slow. That would make it much easier to distinguish expected first-index cost from an avoidable performance issue.

[EnoroF]

I use latest version of reflex and use 'rfx index' to index the UnrealEngine/Engine. I have already remove the tree-sitter to comfirm that, it is tree-sitter cause the problem for large c++ problem. the pure trigram works well for large c++ project in reflex.