# \_fixnum slow? (despite docs)

**URL:** <https://racket.discourse.group/t/fixnum-slow-despite-docs/3409>\
**Category:** Questions & Answers\
**Created:** [December 11, 2024, 1:58pm UTC](https://racket.discourse.group/t/fixnum-slow-despite-docs/3409 "2024-12-11T13:58:08Z")\
**Posts on this page:** 1\
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**Author:** ![LiberalArtist](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/liberalartist/32/151_2.png) [@LiberalArtist](https://racket.discourse.group/u/LiberalArtist)\
**Post date:** [December 21, 2024, 10:14pm UTC](https://racket.discourse.group/t/fixnum-slow-despite-docs/3409/10 "2024-12-21T22:14:04Z")

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> [@mflatt](#):
>
> A Chez Scheme variant of `plus` runs in 3ms instead of 13ms, which reflects overhead still added by Racket's more dynamic FFI.

If @Laurent.O needed the extra performance in the mean time, would using `vm-eval` to access the Chez Scheme FFI work? Or maybe it would be better to write a Chez Scheme library and access it as you explained in [Calling into a Chez Scheme library from Racket -- imported symbol rewritten in vm-eval? - #9 by mflatt](https://racket.discourse.group/t/calling-into-a-chez-scheme-library-from-racket-imported-symbol-rewritten-in-vm-eval/2257/9)? Or do those e.g. inhibit inlining such that it wouldn't pay off?

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