# Plotting slow
**URL:** https://discourse.julialang.org/t/plotting-slow/111083
**Category:** Performance
**Created:** [March 3, 2024, 8:07am UTC](https://discourse.julialang.org/t/plotting-slow/111083 "2024-03-03T08:07:42Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Fourier](https://discourse.julialang.org/u/Fourier)
#### Post date: [March 3, 2024, 8:07am UTC](https://discourse.julialang.org/t/plotting-slow/111083/1 "2024-03-03T08:07:42Z")
We are currently working on a simulation and the bottleneck is plotting.
We are plotting a grid of dimension 1000 x 2000 and saving it.
```julia
T_c_hm = heatmap(x, y, transpose(T_c_renh), size = (1000, 400), clim=(0, 0.3))
savefig("run/T_c_$it_text.png")
T_s_hm = heatmap(x, y, transpose(T_s_renh), size = (1000, 400), clim=(0, 1.0))
savefig("run/T_s_$it_text.png")
u_hm = heatmap(x, y, transpose(v_renh), size = (1000, 400), clim=(0,0.3))
savefig("run/u_$it_text.png")
```
We tried using `gr()` with no avail.
---
### Author:  [@gdalle](https://discourse.julialang.org/u/gdalle)
#### Post date: [March 3, 2024, 8:08am UTC](https://discourse.julialang.org/t/plotting-slow/111083/2 "2024-03-03T08:08:36Z")
Maybe try Makie.jl?
[https://docs.makie.org/stable/reference/plots/heatmap/index.html](https://docs.makie.org/stable/reference/plots/heatmap/index.html)
---
### Author:  [@jheinen](https://discourse.julialang.org/u/jheinen)
#### Post date: [March 3, 2024, 8:58am UTC](https://discourse.julialang.org/t/plotting-slow/111083/3 "2024-03-03T08:58:31Z")
What would you expect?
```julia
using GR
@time heatmap(randn(1000,2000))
0.197676 seconds (8.00 M allocations: 160.242 MiB, 24.41% gc time)
```
Do you have a complete MWE?
---
### Author:  [@Fourier](https://discourse.julialang.org/u/Fourier)
#### Post date: [March 3, 2024, 9:08am UTC](https://discourse.julialang.org/t/plotting-slow/111083/5 "2024-03-03T09:08:26Z")
Its a bit frustrating when you have an 80 Terraflop GPU that does all the computation in 20 ms and then taking 200 ms per plot, so I guess we are going to implement it our own. Is there a fast png library that wont bottleneck again?
---
### Author:  [@mkitti](https://discourse.julialang.org/u/mkitti)
#### Post date: [March 3, 2024, 9:20am UTC](https://discourse.julialang.org/t/plotting-slow/111083/6 "2024-03-03T09:20:47Z")
Perhaps you could save this as an image rather than trying to plot it as a heatmap?
---
### Author:  [@jar1](https://discourse.julialang.org/u/jar1)
#### Post date: [March 3, 2024, 9:29am UTC](https://discourse.julialang.org/t/plotting-slow/111083/7 "2024-03-03T09:29:01Z")
If you’re interested in GPU plotting, I would at least consider if [GLMakie](https://docs.makie.org/stable/explanations/backends/glmakie/index.html) meets your needs.
```julia
using GLMakie
julia> @time let
f = Figure(size=(2000,1000))
ax = Axis(f[1, 1])
centers_x = 1:5
centers_y = 6:10
data = reshape(rand(25), 5, 5)
heatmap!(ax, centers_x, centers_y, data)
save("/tmp/my.png", f)
end
0.025841 seconds (96.64 k allocations: 8.738 MiB)
```
---
### Author:  [@Fourier](https://discourse.julialang.org/u/Fourier)
#### Post date: [March 4, 2024, 12:57pm UTC](https://discourse.julialang.org/t/plotting-slow/111083/8 "2024-03-04T12:57:43Z")
Very nice, thanks a lot. The solution we had at the end was using ParralelStencil
```julia
@parallel_indices (i, j) function heatmap_para!(image, array, min_val, max_val, table)
x = (array[i, j] - min_val) / (max_val - min_val)
for k in 1:3
col = 0.0
for l in 1:6
col *= x
col += table[k, 7-l]
end
image[j, i, k] = clamp(col, 0, 1)
end
return nothing
end
```