# Julia 1.3 order of magnitude slowdown in function
**URL:** https://discourse.julialang.org/t/julia-1-3-order-of-magnitude-slowdown-in-function/32691
**Category:** Performance
**Created:** [December 25, 2019, 12:55pm UTC](https://discourse.julialang.org/t/julia-1-3-order-of-magnitude-slowdown-in-function/32691 "2019-12-25T12:55:20Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@joshua\_jones](https://discourse.julialang.org/u/joshua_jones)
#### Post date: [December 25, 2019, 12:55pm UTC](https://discourse.julialang.org/t/julia-1-3-order-of-magnitude-slowdown-in-function/32691/1 "2019-12-25T12:55:20Z")
Cross-posted from [https://github.com/JuliaLang/julia/issues/34195](https://github.com/JuliaLang/julia/issues/34195)
I’m noticing an order-of-magnitude slowdown in a custom function to parse “sample list” files (one ASCII value per line) to Float32 arrays. Any ideas what could be causing this?
Offending function here: [https://github.com/jpjones76/SeisIO.jl/blob/master/src/Utils/Parsing/streams.jl](https://github.com/jpjones76/SeisIO.jl/blob/master/src/Utils/Parsing/streams.jl)
Affects my ASCII readers for SLIST and Lennartz SLIST files.
Before 1.3.0, `X[i] = stream_float(io, 0x00)` was 2-3x faster than `v = readline(io); X[i] = parse(Float32, v)`. Now `stream_float` is 4x slower than `readline` + `parse`. I actually need the old speeds if possible, so any alternate syntax suggestions would be welcomed.
MWE
```julia
# install, get a test file
using Pkg
Pkg.add("BenchmarkTools")
Pkg.add("SeisIO")
run(`wget https://github.com/jpjones76/SeisIO-TestData/raw/master/SampleFiles/ASCII/0215162000.c00`)
# MWE
using BenchmarkTools
import SeisIO:stream_float
io = open("0215162000.c00", "r")
nx = 225000
X = Array(Float32, 1){undef, nx}
@benchmark (seekstart($io); readline($io); @inbounds for i in 1:$nx; $X[i] = stream_float($io, 0x00); end)
```
Example outputs follow. I benchmarked this on a Dell laptop running Ubuntu 18.04 (bionic), kernel 5.0.0-37-generic, CPU Intel(R) Core™ i7-6820HQ CPU @ 2.70GHz, 16 GB RAM.
Julia 1.0.5
```julia
BenchmarkTools.Trial:
memory estimate: 272 bytes
allocs estimate: 2
--------------
minimum time: 25.533 ms (0.00% GC)
median time: 25.701 ms (0.00% GC)
mean time: 25.867 ms (0.00% GC)
maximum time: 30.592 ms (0.00% GC)
--------------
samples: 194
evals/sample: 1
```
Julia 1.2.0:
```julia
memory estimate: 272 bytes
allocs estimate: 2
--------------
minimum time: 24.738 ms (0.00% GC)
median time: 24.850 ms (0.00% GC)
mean time: 24.910 ms (0.00% GC)
maximum time: 27.172 ms (0.00% GC)
--------------
samples: 201
evals/sample: 1
```
Julia 1.3.0:
```julia
BenchmarkTools.Trial:
memory estimate: 272 bytes
allocs estimate: 2
--------------
minimum time: 236.738 ms (0.00% GC)
median time: 237.059 ms (0.00% GC)
mean time: 237.833 ms (0.00% GC)
maximum time: 245.997 ms (0.00% GC)
--------------
samples: 22
evals/sample: 1
```
The relative contributions of the `seekstart` and `readline` commands are trivial.
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [December 25, 2019, 1:19pm UTC](https://discourse.julialang.org/t/julia-1-3-order-of-magnitude-slowdown-in-function/32691/2 "2019-12-25T13:19:59Z")
Referencing my reply in [Julia 1.3 order of magnitude slowdown in function · Issue #34195 · JuliaLang/julia · GitHub](https://github.com/JuliaLang/julia/issues/34195)
> `read` is now thread safe which requires acquiring a lock so reading things byte by byte (small reads in general) has slowed down. You could perhaps try [GitHub - JuliaIO/BufferedStreams.jl: Fast composable IO streams](https://github.com/BioJulia/BufferedStreams.jl). I do think it would be good to have a goto solution for this in Base (perhaps there already is and I just don’t know about it).