# Nerd-sniping: can you make this faster?

**URL:** <https://discourse.julialang.org/t/nerd-sniping-can-you-make-this-faster/132793>\
**Category:** Performance\
**Created:** [September 30, 2025, 8:10pm UTC](https://discourse.julialang.org/t/nerd-sniping-can-you-make-this-faster/132793 "2025-09-30T20:10:34Z")\
**Posts on this page:** 1\
**Showing post:** 25

<div class="post-metadata">

**Author:** ![lmiq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lmiq/32/18314_2.png) [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Post date:** [October 1, 2025, 2:11pm UTC](https://discourse.julialang.org/t/nerd-sniping-can-you-make-this-faster/132793/25 "2025-10-01T14:11:08Z")

</div>

I’m settling down with this version, based on Zentrik’s suggestion:

```julia-auto
using SIMD: VecRange
using StaticArrays
using BenchmarkTools

function update_dot_exposure!(deltaxy, dot_cache, exposed_i, rj_sq, ::Val{N}) where {N}
    lastN = N * (length(exposed_i) ÷ N)
    lane = VecRange{N}(0)
    @inbounds for i in 1:N:lastN
        if any(exposed_i[lane + i])
            pos_x = dot_cache.x[lane + i] + deltaxy[1]
            pos_y = dot_cache.y[lane + i] + deltaxy[2]
            pos_z = dot_cache.z[lane + i] + deltaxy[3]
            exposed_i[lane + i] &= sum(abs2, (pos_x, pos_y, pos_z)) >= rj_sq
        end
    end
    # Remaining 
    @inbounds for i in lastN+1:length(exposed_i)
        pos_x = dot_cache.x[i] + deltaxy[1]
        pos_y = dot_cache.y[i] + deltaxy[2]
        pos_z = dot_cache.z[i] + deltaxy[3]
        exposed_i[i] &= sum(abs2, (pos_x, pos_y, pos_z)) >= rj_sq
    end
    return exposed_i
end

struct DotCache{T}
    x::Vector{T}
    y::Vector{T}
    z::Vector{T}
end

function data_soa()
    x = rand(SVector{3,Float32}) 
    y = rand(SVector{3,Float32})
    dot_cache = DotCache(rand(Float32,200), rand(Float32,200), rand(Float32,200))
    exposed_i=[rand() > 0.8 for _ in 1:200]
    rj_sq=0.1f0
    N=Val(16)
    return x-y, dot_cache, exposed_i, rj_sq, N
end

```

With the following performance:

```julia-repl
julia> @benchmark update_dot_exposure!($(data_soa())...)
BenchmarkTools.Trial: 10000 samples with 996 evaluations per sample.
 Range (min … max): 22.367 ns … 47.081 ns ┊ GC (min … max): 0.00% … 0.00%
 Time (median): 23.172 ns ┊ GC (median): 0.00%
 Time (mean ± σ): 23.140 ns ± 0.437 ns ┊ GC (mean ± σ): 0.00% ± 0.00%

             ▅▆ ▃█▆ ▂ ▂
  ▇▇▁▁▁▁▁▁▁▃▁███▅▆▄▄▅▆▅▄███▆▆▄▄▅▆▄▅▅▆██▄▆▆▆▅▄▅▅▅▅▇▆▅▇███▇▆▆▆▇ █
  22.4 ns Histogram: log(frequency) by time 24.4 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.

```

Feel free to squeeze it further 🙂

Thanks all for the help!

---

_[View the full topic](https://discourse.julialang.org/t/nerd-sniping-can-you-make-this-faster/132793)._