# Running time

**URL:** <https://discourse.julialang.org/t/running-time/67462>\
**Category:** Performance\
**Created:** [August 31, 2021, 10:42pm UTC](https://discourse.julialang.org/t/running-time/67462 "2021-08-31T22:42:43Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![tortijazz](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tortijazz/32/28754_2.png) [@tortijazz](https://discourse.julialang.org/u/tortijazz)\
**Post date:** [August 31, 2021, 10:42pm UTC](https://discourse.julialang.org/t/running-time/67462/1 "2021-08-31T22:42:43Z")

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Hi everybody,

I was making simulations with Flux.jl, DiffEqFlux.jl, Optim.jl, DiffEqSensitivity.jl and OrdinaryDiffEq.jl in Julia-1.5.2 and I saw that there was a new stable release (1.6.2 version), so I did upgrade Julia to the ‘new’ one (and removed everything about 1.5.2 version), nevertheless I realized the running time (making exactly the same simulations) was around 12x slower than before. Anybody knows why this happens or knows how to recover an old version of Julia (1.5.2) on Mac?

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**Author:** ![brett-mahar](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/brett-mahar/32/27671_2.png) [@brett-mahar](https://discourse.julialang.org/u/brett-mahar)\
**Post date:** [August 31, 2021, 11:13pm UTC](https://discourse.julialang.org/t/running-time/67462/2 "2021-08-31T23:13:59Z")

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Hi,

To use a different version on linux (Mac should be quite similar), I:

Go to the downloads page and download the version you want.  
tar zxvf julia-latest-linuxaarch64.tar.gz  
mv julia-latest-XXX/ julia-2021-XX-XX

Then in .profile (your username’s .profile and root’s profile), add:  
PATH=/home/XXX/.julia/julia-XXX/bin/:…

Then after you reboot and launch Julia, you will get that version.

If using scripts, you can use the shebang at the top of the script:

#!/usr/bin/env julia (to use the version you specified in .profile)  
OR  
#!/home/XXX/.julia/julia-1.0.5/bin/julia (to use a specific version only for that script)

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**Author:** ![brett-mahar](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/brett-mahar/32/27671_2.png) [@brett-mahar](https://discourse.julialang.org/u/brett-mahar)\
**Post date:** [August 31, 2021, 11:39pm UTC](https://discourse.julialang.org/t/running-time/67462/3 "2021-08-31T23:39:38Z")

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Hi again @tortijazz

Just in case you are not familiar with system administration things, I realised I should be more specific, in .profile you still need to keep what is already there (or you will bork your system), so it should be something like:

PATH=/home/brett/.julia/julia-2021-08-26/bin/:/scripts:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/vendor\_perl:/usr/bin/core\_perl

Also, if you want to run your program with specific versions of packages, you can look at setting up a `project`:

> **[How to setup Project Environments in Julia](https://towardsdatascience.com/how-to-setup-project-environments-in-julia-ec8ae73afe9c)**
>
> An introduction to Julia’s built-in package manager for generating project environments and managing package dependencies.

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<div class="post-metadata">

**Author:** ![tortijazz](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tortijazz/32/28754_2.png) [@tortijazz](https://discourse.julialang.org/u/tortijazz)\
**Post date:** [September 1, 2021, 5:40am UTC](https://discourse.julialang.org/t/running-time/67462/4 "2021-09-01T05:40:02Z")

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Brett-mahar, thank you very much. You helped me a lot.

Best,  
Gustavo

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**Author:** ![mkitti](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mkitti/32/12459_2.png) [@mkitti](https://discourse.julialang.org/u/mkitti)\
**Post date:** [September 1, 2021, 5:52am UTC](https://discourse.julialang.org/t/running-time/67462/5 "2021-09-01T05:52:24Z")

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It would be helpful if you could narrow down what is slower in Julia 1.6.2. If you are adventurous, it will also be interesting to try the nightly builds to see if the issue may have already been resolved.

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**Author:** ![brett-mahar](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/brett-mahar/32/27671_2.png) [@brett-mahar](https://discourse.julialang.org/u/brett-mahar)\
**Post date:** [September 1, 2021, 6:55am UTC](https://discourse.julialang.org/t/running-time/67462/6 "2021-09-01T06:55:23Z")

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@tortijazz  
Gustavo, I’m happy I could help!