# OCaml 5 performance

**URL:** <https://discuss.ocaml.org/t/ocaml-5-performance/15014>\
**Category:** Ecosystem\
**Tags:** multicore, profiling, eio, performance\
**Created:** [July 23, 2024, 9:53am UTC](https://discuss.ocaml.org/t/ocaml-5-performance/15014 "2024-07-23T09:53:30Z")\
**Posts on this page:** 1\
**Showing post:** 1

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**Author:** ![talex5](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/talex5/32/353_2.png) [@talex5](https://discuss.ocaml.org/u/talex5)\
**Post date:** [July 23, 2024, 9:53am UTC](https://discuss.ocaml.org/t/ocaml-5-performance/15014/1 "2024-07-23T09:53:30Z")

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I’ve been trying out some tools to investigate performance problems in my OCaml programs and I’ve written up my experiences here in case other people find it useful:

- [OCaml 5 performance problems - Thomas Leonard's blog](https://roscidus.com/blog/blog/2024/07/22/performance/)
- [OCaml 5 performance part 2 - Thomas Leonard's blog](https://roscidus.com/blog/blog/2024/07/22/performance-2/)

The first post examines a case of slow IO in a concurrent Eio program, and the second looks at poor GC performance in a multicore app.

In particular, it seems that minor GC performance is very sensitive to other work running on the machine, since any domain being late will trigger the others to sleep, e.g.

 ![image](https://us1.discourse-cdn.com/flex020/uploads/ocaml/original/2X/e/e821895b934f9519f84d0e52f28057bb30274092.png)

I’d be interested to know if others can shed more light on this, or have other profiling tools they’ve found useful.

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