# Rethinking optimization, lower ok for all Julia code (for e.g. faster startup) as a default?

**URL:** https://discourse.julialang.org/t/rethinking-optimization-lower-ok-for-all-julia-code-for-e-g-faster-startup-as-a-default/39843
**Category:** General Usage
**Created:** [May 20, 2020, 4:22pm UTC](https://discourse.julialang.org/t/rethinking-optimization-lower-ok-for-all-julia-code-for-e-g-faster-startup-as-a-default/39843 "2020-05-20T16:22:39Z")
**Posts on this page:** 1
**Showing post:** 8

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### Author: ![Marc.Cox](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marc.cox/32/7514_2.png) [@Marc.Cox](https://discourse.julialang.org/u/Marc.Cox)
#### Post date: [April 12, 2021, 3:26pm UTC](https://discourse.julialang.org/t/rethinking-optimization-lower-ok-for-all-julia-code-for-e-g-faster-startup-as-a-default/39843/8 "2021-04-12T15:26:43Z")

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> [@Jeff Bezanson remarks on LLVM "getting slower and slower"](https://discourse.julialang.org/t/jeff-bezanson-remarks-on-llvm-getting-slower-and-slower/39637/15):
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> Thx @ImreSamu, Support for A JIT compiler should operate on the Pareto rule principle "… for many outcomes, roughly 80% of consequences come from 20% of the causes (the “vital few”).[1] " @@ [Pareto principle - Wikipedia](https://en.wikipedia.org/wiki/Pareto_principle) Google Engineers contributed to LLVM 12 RC1 making “Machine Function Splitter” code generation optimization pass for splitting code functions into hot and cold parts. They are doing this stemming from their research that in roughly half of code functions that MORE than …

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