# JuMP is slow in generating block PSD constraints
**URL:** https://discourse.julialang.org/t/jump-is-slow-in-generating-block-psd-constraints/65186
**Category:** Optimization (Mathematical)
**Tags:** jump
**Created:** [July 23, 2021, 2:54pm UTC](https://discourse.julialang.org/t/jump-is-slow-in-generating-block-psd-constraints/65186 "2021-07-23T14:54:47Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Thomas](https://discourse.julialang.org/u/Thomas)
#### Post date: [July 23, 2021, 2:54pm UTC](https://discourse.julialang.org/t/jump-is-slow-in-generating-block-psd-constraints/65186/1 "2021-07-23T14:54:47Z")
Could an expert help me speed up the following code? In particular,
- Have I used the performance tips ([https://jump.dev/JuMP.jl/stable/tutorials/Getting%20started/performance\_tips/](https://jump.dev/JuMP.jl/stable/tutorials/Getting%20started/performance_tips/)) correctly? That is only generate expressions inside macro.
- Does it help to use sparse matrix?
- Does multithreading the `for` loop with Threads.@threads help?
Note that `computeMatrix` is not a bottleneck in my case, however the bottleneck could be with the fact that `length(x)` is large.
Edit: I did a better benchmark this time and the slowdown is mainly due to `computeMatrix` as caused by having large `length(x)` so it seems this is not a JuMP problem.
```julia
for blk in blocks
if size(blk, 1) > 1
println("adding PSD constraint for block of size $(size(blk))")
@constraint(m, sum(x[i] .* computeMatrix(i, blk) for i in 1:length(x)) in PSDCone())
else
println("adding inequality constraint")
@constraint(m, sum(x[i] .* computeMatrix(i, blk) for i in 1:length(x)) .>= 0)
end
end
```
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [July 23, 2021, 6:38pm UTC](https://discourse.julialang.org/t/jump-is-slow-in-generating-block-psd-constraints/65186/2 "2021-07-23T18:38:28Z")
Please provide a reproducible example
---
### Author:  [@Thomas](https://discourse.julialang.org/u/Thomas)
#### Post date: [July 24, 2021, 2:48pm UTC](https://discourse.julialang.org/t/jump-is-slow-in-generating-block-psd-constraints/65186/3 "2021-07-24T14:48:41Z")
Nevermind, I got it to work faster by improving the bottleneck in `computeMatrix`. Multithreading does not seem to help much with the speedup.