diff --git a/src/nonlocal.jl b/src/nonlocal.jl
index 34f363f..159f96b 100644
--- a/src/nonlocal.jl
+++ b/src/nonlocal.jl
@@ -29,61 +29,38 @@ function _local_bound_correlation(G::Array{T,N}; marg::Bool = true) where {T<:Re
     end
 
     chunks = _partition(outs[N]^(ins[N] - marg), Threads.nthreads())
-    ins2 = ins
     G2 = G #workaround for https://github.com/JuliaLang/julia/issues/15276
     tasks = map(chunks) do chunk
-        Threads.@spawn _local_bound_correlation_recursive_top(chunk, ins2, G2; marg)
+        Threads.@spawn _local_bound_correlation_recursive!(copy(G2), chunk, marg)
     end
     score = maximum(fetch.(tasks))
     return score
 end
 
-Base.@propagate_inbounds function _local_bound_correlation_recursive_top(
+function _local_bound_correlation_recursive!(
+    A::Array{T,N},
     chunk,
-    m::NTuple{N,Int},
-    A::Array{T,N};
-    marg = true
+    marg = true,
+    m = size(A),
+    tmp = [zeros(T, m[1:i]...) for i ∈ 1:N-1],
+    offset = [zeros(T, m[1:i]...) for i ∈ 1:N-1],
+    ind = [zeros(Int8, m[i] - marg) for i ∈ 2:N],
 ) where {T<:Real,N}
-    tmp = [zeros(T, m[1:i]) for i ∈ 1:N-1]
-    offset = [zeros(T, m[1:i]) for i ∈ 1:N-1]
-    ind = [zeros(Int8, m[i] - marg) for i ∈ 2:N]
-    digits!(ind[N-1], chunk[1] - 1; base = 2)
-    tmp_end::Array{T,N - 1} = tmp[N-1]
-    offset_end::Array{T,N - 1} = offset[N-1]
-    _compute_offset!(offset_end, A, marg)
-    score = typemin(T)
-    A2 = 2 * A
-    @inbounds for _ ∈ chunk[1]:chunk[2]
-        tmp_end .= offset_end
-        _tensor_contraction!(tmp_end, A2, ind[N-1], marg)
-        @views temp_score =
-            _local_bound_correlation_recursive(tmp_end, marg, m[1:N-1], tmp[1:N-2], offset[1:N-2], ind[1:N-2])
-        if temp_score > score
-            score = temp_score
+    tmp_end::Array{T,N-1} = tmp[N-1]
+    offset_end::Array{T,N-1} = offset[N-1]
+    sum!(offset_end, A)
+    A .*= 2
+    if marg
+        for ci ∈ CartesianIndices(offset_end)
+            offset_end[ci] -= A[ci, 1]
         end
-        _update_odometer!(ind[N-1], 2)
     end
-    return score
-end
-
-Base.@propagate_inbounds function _local_bound_correlation_recursive(
-    A::Array{T,N},
-    marg,
-    m,
-    tmp,
-    offset,
-    ind
-) where {T<:Real,N}
-    tmp_end::Array{T,N - 1} = tmp[N-1]
-    offset_end::Array{T,N - 1} = offset[N-1]
-    _compute_offset!(offset_end, A, marg)
+    offset_end .*= -1
     score = typemin(T)
-    A2 = 2 * A
-    @inbounds for _ ∈ 0:2^(m[N]-marg)-1
+    for _ ∈ chunk[1]:chunk[2]
         tmp_end .= offset_end
-        _tensor_contraction!(tmp_end, A2, ind[N-1], marg)
-        @views temp_score =
-            _local_bound_correlation_recursive(tmp_end, marg, m[1:N-1], tmp[1:N-2], offset[1:N-2], ind[1:N-2])
+        _tensor_contraction!(tmp_end, A, ind[N-1], marg)
+        @views temp_score = _local_bound_correlation_recursive!(tmp_end, (0, 2^(m[N-1]-marg)-1), marg, m[1:N-1], tmp[1:N-2], offset[1:N-2], ind[1:N-2])
         if temp_score > score
             score = temp_score
         end
@@ -92,7 +69,7 @@ Base.@propagate_inbounds function _local_bound_correlation_recursive(
     return score
 end
 
-Base.@propagate_inbounds function _local_bound_correlation_recursive(A::Vector, marg, m, tmp, offset, ind)
+function _local_bound_correlation_recursive!(A::Vector, chunk, marg, m, tmp, offset, ind)
     score = marg ? A[1] : abs(A[1])
     for x ∈ 2:m[1]
         score += abs(A[x])
@@ -101,7 +78,7 @@ Base.@propagate_inbounds function _local_bound_correlation_recursive(A::Vector,
 end
 
 function _tensor_contraction!(tmp, A::Array{T,N}, ind, marg) where {T<:Number,N}
-    @inbounds for x ∈ eachindex(ind)
+    for x ∈ eachindex(ind)
         if ind[x] == 1
             for ci ∈ CartesianIndices(tmp)
                 tmp[ci] += A[ci, x+marg]
@@ -110,16 +87,6 @@ function _tensor_contraction!(tmp, A::Array{T,N}, ind, marg) where {T<:Number,N}
     end
 end
 
-function _compute_offset!(offset_end, A, marg)
-    sum!(offset_end, A)
-    if marg
-        for ci ∈ CartesianIndices(offset_end)
-            offset_end[ci] -= 2 * A[ci, 1]
-        end
-    end
-    offset_end .*= -1
-end
-
 function _local_bound_probability(G::Array{T,N2}) where {T<:Real,N2}
     @assert iseven(N2)
     N = N2 ÷ 2