Om ChillureandMax Brunsfeld
5ddee8c145
#### Context When tree-sitter parses a file with broken syntax (e.g. a large partial SQL `VALUES` clause, or any language where a large chunk becomes invalid), it can produce a single `ERROR` node spanning thousands of lines. On every render frame, Zed queries this tree for syntax highlights via `SyntaxMapCaptures`. Previously, only `set_byte_range` was applied to the query cursor - this limits which captures are *returned*, but tree-sitter still had to *traverse* the entire ERROR subtree to find them, causing O(file size) work per frame and making scrolling/editing visibly laggy. The fix applies `set_containing_byte_range` to the highlight query cursor, mirroring what `SyntaxMapMatches` already does for indentation and bracket queries. This tells tree-sitter to skip subtrees that extend far beyond the visible window, reducing traversal to the visible range only. **Note:** This fix eliminates the main freeze/stall caused by full-tree traversal. A small amount of lag may still occur on very large broken files, as tree-sitter still needs to parse the error-recovery structure. Further improvements would require deeper changes to tree-sitter's query execution or incremental parsing. #### Closes #52390 #### How to Review Small change — focus on [syntax_map.rs:1119-1123](crates/language/src/syntax_map.rs#L1119) (the fix) and the `containing_byte_range_for_captures` helper below it. Compare with the existing `SyntaxMapMatches::new` path (line ~1255) which uses the same pattern. #### Self-Review Checklist - [x] I've reviewed my own diff for quality, security, and reliability - [x] Unsafe blocks (if any) have justifying comments - [x] The content is consistent with the [UI/UX checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable #### Video [Screencast from 2026-03-26 14-19-19.webm](https://github.com/user-attachments/assets/6628492a-f013-438a-836a-2740f6e2f266) #### Note : Reopens previous work from closed PR #52475 (fork was deleted) Release Notes: - Fixed laggy scrolling and editing in files with large broken syntax regions (e.g. incomplete SQL `VALUES` clauses or large invalid blocks in any language) --------- Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Zed
Welcome to Zed, a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.
Installation
On macOS, Linux, and Windows you can download Zed directly or install Zed via your local package manager (macOS/Linux/Windows).
Other platforms are not yet available:
- Web (tracking issue)
Developing Zed
Contributing
See CONTRIBUTING.md for ways you can contribute to Zed.
Also... we're hiring! Check out our jobs page for open roles.
Licensing
License information for third party dependencies must be correctly provided for CI to pass.
We use cargo-about to automatically comply with open source licenses. If CI is failing, check the following:
- Is it showing a
no license specifiederror for a crate you've created? If so, addpublish = falseunder[package]in your crate's Cargo.toml. - Is the error
failed to satisfy license requirementsfor a dependency? If so, first determine what license the project has and whether this system is sufficient to comply with this license's requirements. If you're unsure, ask a lawyer. Once you've verified that this system is acceptable add the license's SPDX identifier to theacceptedarray inscript/licenses/zed-licenses.toml. - Is
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Sponsorship
Zed is developed by Zed Industries, Inc., a for-profit company.
If you’d like to financially support the project, you can do so via GitHub Sponsors. Sponsorships go directly to Zed Industries and are used as general company revenue. There are no perks or entitlements associated with sponsorship.