Apply suggestions from code review

Co-authored-by: David Müller-Widmann <[email protected]>

Author: andreasnoack

benchmark/benchmarks.jl

@@ -4,7 +4,7 @@ const SUITE = BenchmarkGroup()
 
 SUITE["random"] = BenchmarkGroup()
 
-for i in 2:4
+for i in 2:6
     n = 10^i
     x = rand(MersenneTwister(42), n)
     y = sqrt.(x)

src/Loess.jl

@@ -299,7 +299,7 @@ function predict(
         else
             [s * norm(_hatmatrix_x(model, _x)) for _x in x_v]
         end
-        lower = [_x - qt * _sₓ for (_x, _sₓ) in zip(predictions, sₓ)]
+        lower = muladd(-qt, sₓ, predictions)
         upper = [_x + qt * _sₓ for (_x, _sₓ) in zip(predictions, sₓ)]
         return LoessPrediction(predictions, lower, upper, sₓ, δ₁, δ₂, s, ρ)
     end