diff --git a/test/assembly_benchmark.jl b/test/assembly_benchmark.jl
new file mode 100644
index 000000000..d9fb4e0fd
--- /dev/null
+++ b/test/assembly_benchmark.jl
@@ -0,0 +1,139 @@
+
+using BenchmarkTools
+using SparseArrays, LinearAlgebra
+using Gridap, Gridap.FESpaces, Gridap.Algebra
+
+function nzindex(A::SparseArrays.AbstractSparseMatrixCSC, i0::Integer, i1::Integer)
+  if !(1 <= i0 <= size(A, 1) && 1 <= i1 <= size(A, 2)); throw(BoundsError()); end
+  ptrs = SparseArrays.getcolptr(A)
+  r1 = Int(ptrs[i1])
+  r2 = Int(ptrs[i1+1]-1)
+  (r1 > r2) && return -1
+  r1 = searchsortedfirst(rowvals(A), i0, r1, r2, Base.Order.Forward)
+  ((r1 > r2) || (rowvals(A)[r1] != i0)) ? 0 : r1
+end
+
+function precompute_nzindex(A,a::Algebra.AllocationCOO)
+  precompute_nzindex(A,a.I,a.J)
+end
+
+function precompute_nzindex(A,I,J)
+  K = zeros(Int32,length(I))
+  for (p,(i,j)) in enumerate(zip(I,J))
+      if i < 1 || j < 1
+          continue
+      end
+      K[p] = nzindex(A,i,j)
+  end
+  K
+end
+
+function sparse_matrix!(A,V,K;reset=true)
+  if reset
+      LinearAlgebra.fillstored!(A,0)
+  end
+  A_nz = nonzeros(A)
+  for (k,v) in zip(K,V)
+      if k < 1
+          continue
+      end
+      A_nz[k] += v
+  end
+  A
+end
+
+function Algebra.CounterCOO(::Algebra.SparseMatrixBuilder{T},axes) where T
+  Algebra.CounterCOO{T}(axes)
+end
+
+function assemble_coo(a,matdata;reuse=false)
+  m1 = Algebra.CounterCOO(get_matrix_builder(a),(get_rows(a),get_cols(a)))
+  symbolic_loop_matrix!(m1,a,matdata)
+  m2 = nz_allocation(m1)
+  numeric_loop_matrix!(m2,a,matdata)
+  m3 = create_from_nz(m2)
+  if reuse
+    return m3, (m2,precompute_nzindex(m3,m2))
+  end
+  m3
+end
+
+function assemble_coo!(mat,a,matdata,cache)
+  m2, K = cache
+  m2.counter.nnz = 0
+  numeric_loop_matrix!(m2,a,matdata)
+  sparse_matrix!(mat,m2.V,K,reset=true)
+end
+
+###########
+mutable struct CachedInserterCOO{Tv,Ti,Ti2}
+  nnz :: Int
+  mat :: SparseMatrixCSC{Tv,Ti}
+  K :: Vector{Ti2}
+
+  function CachedInserterCOO(mat::SparseMatrixCSC{Tv,Ti}, K::Vector{Ti2}) where {Tv,Ti,Ti2}
+    new{Tv,Ti,Ti2}(0,mat,K)
+  end
+end
+
+Algebra.LoopStyle(::Type{<:CachedInserterCOO}) = Loop()
+
+@noinline function Algebra.add_entry!(::typeof(+),a::CachedInserterCOO,v,i,j)
+  a.nnz = a.nnz + 1
+  k = a.K[a.nnz]
+  a.mat.nzval[k] += v
+  nothing
+end
+
+function assemble_coo_opt(a,matdata;reuse=false)
+  m1 = Algebra.CounterCOO(get_matrix_builder(a),(get_rows(a),get_cols(a)))
+  symbolic_loop_matrix!(m1,a,matdata)
+  m2 = nz_allocation(m1)
+  numeric_loop_matrix!(m2,a,matdata)
+  m3 = create_from_nz(m2)
+  if reuse
+    K = precompute_nzindex(m3,m2)
+    return m3, K
+  end
+  m3
+end
+
+function assemble_coo_opt!(mat,a,matdata,K)
+  LinearAlgebra.fillstored!(mat,zero(eltype(mat)))
+  m = CachedInserterCOO(mat,K)
+  numeric_loop_matrix!(m,a,matdata)
+  mat
+end
+
+model = CartesianDiscreteModel((0,1,0,1),(100,100))
+
+order = 1
+reffe = ReferenceFE(lagrangian, Float64, order)
+V = TestFESpace(model, reffe)
+
+qdegree = 2*order
+Ω  = Triangulation(model)
+dΩ = Measure(Ω, qdegree)
+Γ  = Boundary(model)
+dΓ = Measure(Γ, qdegree)
+a(u,v) = ∫(∇(u)⋅∇(v))dΩ + ∫(u*v)dΓ - ∫((∇⋅u) ⋅ (∇⋅v))dΩ
+
+u = get_trial_fe_basis(V)
+v = get_fe_basis(V)
+matdata = collect_cell_matrix(V,V,a(u,v))
+
+assem = SparseMatrixAssembler(V,V)
+
+A1 = assemble_matrix(assem,matdata)
+A2, cache2 = assemble_coo(assem,matdata;reuse=true);
+assemble_coo!(A2,assem,matdata,cache2)
+A3, cache3 = assemble_coo_opt(assem,matdata;reuse=true);
+assemble_coo_opt!(A3,assem,matdata,cache3)
+A1 ≈ A2 ≈ A3
+
+@benchmark assemble_matrix($assem,$matdata)
+@benchmark assemble_coo($assem,$matdata)
+@benchmark assemble_coo_opt($assem,$matdata)
+@benchmark assemble_matrix!($A1,$assem,$matdata)
+@benchmark assemble_coo!($A2,$assem,$matdata,$cache2)
+@benchmark assemble_coo_opt!($A3,$assem,$matdata,$cache3)
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