blog: Table v9 type perf blog#979
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📝 WalkthroughWalkthroughThis PR adds a new blog post documenting the TypeScript type-checking performance improvements made to TanStack Table V9 from alpha.54 through beta.12, detailing the shift from conditional unions to feature maps, optimization techniques, measurement methodology, and practical guidance for developers. ChangesTypeScript Performance Optimization Blog Post
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Actionable comments posted: 2
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@src/blog/tanstack-table-v9-typescript-performance.md`:
- Line 16: Fix the typo in the intro sentence: replace the phrase "turned our to
be one of our bigger optimizations" with "turned out to be one of our bigger
optimizations" so the sentence reads correctly.
- Around line 257-261: The paragraph overstates the safety of the `in out`
variance claim; replace the sentences that say "`in out` annotation is simply
trusted" and "sound to do regardless of the structure" with a more accurate
explanation: state that `in out` asserts invariance for the compiler's
instantiation-based comparisons and can bypass structural variance probing
(i.e., the compiler will use the annotated invariance rather than derive
variance from the type's structure), that this usually only restricts
assignability but can also remove relations the code relies on (as shown by
`TValue` breaking the build), and therefore it should be applied only where
parameters are invariant in practice (keeping the `Table_Internal` and `TValue`
examples as-is to illustrate the benefit and caveat).
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src/blog/tanstack-table-v9-typescript-performance.md
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| title: TypeScript Performance in TanStack Table V9 | ||
| published: 2026-06-13 | ||
| excerpt: TanStack Table V9's types do a lot more than V8's did. Here's how we cut type instantiations by 66-85% across every package between the alpha.54 and beta.11 to keep the editor experience feeling nearly instant. |
Contributor
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"nearly"? why so defensive?
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Author
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In my own experience, there's usually still a noticeable few tenths of a second for the type to pop up. Plus there is still a lot of things going on that make this a slower typescript experience compared to v8. It's just way less of a time cost now and the tradeoffs are worth it.
So I didn't think "nearly" was defensive, just accurate
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| TanStack Table V9 has a much more capable, though more complex, type system than V8. The types in Table may not be as complicated as a project like TanStack Router or Form, but it has still grown more complex in V9 than it ever had been in previous versions. |
Contributor
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is "type system" the right term here?
Member
Author
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I want a better term. What should it be?
Contributor
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"type-level API" maybe?
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| TanStack Table V9 has a much more capable, though more complex, type system than V8. The types in Table may not be as complicated as a project like TanStack Router or Form, but it has still grown more complex in V9 than it ever had been in previous versions. | ||
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| If you had been using the Table V9 alphas, there's a chance that you could feel a bit of slowness in your editor. Good news, though! Between the alpha and the latest beta, we cut TypeScript's type-checking work by 66-85% across every package and example! The latest beta now type-checks faster than our alpha versions from last week by a wide margin, and the editor experience is back to feeling nearly instant. |
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| If you had been using the Table V9 alphas, there's a chance that you could feel a bit of slowness in your editor. Good news, though! Between the alpha and the latest beta, we cut TypeScript's type-checking work by 66-85% across every package and example! The latest beta now type-checks faster than our alpha versions from last week by a wide margin, and the editor experience is back to feeling nearly instant. | ||
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| This post covers where the cost came from, how we measured it, and the specific changes that fixed these issues. One of those changes is a still overlooked TypeScript feature that many library authors still seem to barely use, and it turned our to be one of our bigger optimizations, turning a trade-off into a win across the board. |
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Actionable comments posted: 1
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@src/blog/tanstack-table-v9-typescript-performance.md`:
- Line 14: The headline at line 14 claims a 66-85% improvement "across every
package and example," but the measured data in the tables below shows results
ranging from as low as 36% for examples and 62.1% for `@tanstack/vue-table`, which
fall outside this range. Either widen the percentage range to accurately reflect
all measured improvements (likely 36-85% or similar), or narrow the claim by
removing "across every package and example" and specifying only which packages
or examples achieve the 66-85% improvement. Apply the same correction at line 4,
which contains the identical claim. Ensure the headline numbers align with the
complete data presented in the tables below.
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Actionable comments posted: 2
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@src/blog/tanstack-table-v9-typescript-performance.md`:
- Line 256: Fix the spelling error in the opening sentence of the paragraph that
starts with "The large improvment came from noticing that internal code doesn't
need the feature-conditional view at all." Change the misspelled word
"improvment" to "improvement" to correct the grammar.
- Line 4: The performance range claim of "66-86% across every package and
example" in the excerpt (line 4) and opening line (line 14) is inaccurate based
on the measured data shown below in the document. The core and adapter tables
show improvements from -62.1% to -85.9%, while kitchen-sink examples range from
36% to 79%, making the actual spread 36-86% across all packages and examples.
Update both line 4 and line 14 to either widen the range to 36-86% to cover all
examples, split the claim with separate ranges for core/adapters versus
examples, or remove the specific percentage range entirely and direct readers to
the detailed tables below for the complete performance breakdown.
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src/blog/tanstack-table-v9-typescript-performance.md
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