diff --git a/src/EGraphs/egraph.jl b/src/EGraphs/egraph.jl
index 0a86d91f..5937ddad 100644
--- a/src/EGraphs/egraph.jl
+++ b/src/EGraphs/egraph.jl
@@ -224,22 +224,6 @@ Returns the canonical e-class id for a given e-class.
 
 @inline Base.getindex(g::EGraph, i::Id) = g.classes[IdKey(find(g, i))]
 
-# function canonicalize(g::EGraph, n::VecExpr)::VecExpr
-#   if !v_isexpr(n)
-#     v_hash!(n)
-#     return n
-#   end
-#   l = v_arity(n)
-#   new_n = v_new(l)
-#   v_set_flag!(new_n, v_flags(n))
-#   v_set_head!(new_n, v_head(n))
-#   for i in v_children_range(n)
-#     @inbounds new_n[i] = find(g, n[i])
-#   end
-#   v_hash!(new_n)
-#   new_n
-# end
-
 function canonicalize!(g::EGraph, n::VecExpr)
   v_isexpr(n) || @goto ret
   for i in (VECEXPR_META_LENGTH + 1):length(n)
@@ -253,19 +237,16 @@ end
 
 function lookup(g::EGraph, n::VecExpr)::Id
   canonicalize!(g, n)
-  h = IdKey(v_hash(n))
 
-  haskey(g.memo, n) ? find(g, g.memo[n]) : 0
+  id = get(g.memo, n, zero(Id))
+  iszero(id) ? id : find(g, id)
 end
 
 
 function add_class_by_op(g::EGraph, n, eclass_id)
   key = IdKey(v_signature(n))
-  if haskey(g.classes_by_op, key)
-    push!(g.classes_by_op[key], eclass_id)
-  else
-    g.classes_by_op[key] = [eclass_id]
-  end
+  vec = get!(g.classes_by_op, key, Vector{Id}())
+  push!(vec, eclass_id)
 end
 
 """
@@ -274,7 +255,8 @@ Inserts an e-node in an [`EGraph`](@ref)
 function add!(g::EGraph{ExpressionType,Analysis}, n::VecExpr, should_copy::Bool)::Id where {ExpressionType,Analysis}
   canonicalize!(g, n)
 
-  haskey(g.memo, n) && return g.memo[n]
+  id = get(g.memo, n, zero(Id))
+  iszero(id) || return id
 
   if should_copy
     n = copy(n)
@@ -291,7 +273,7 @@ function add!(g::EGraph{ExpressionType,Analysis}, n::VecExpr, should_copy::Bool)
   g.memo[n] = id
 
   add_class_by_op(g, n, id)
-  eclass = EClass{Analysis}(id, VecExpr[n], Pair{VecExpr,Id}[], make(g, n))
+  eclass = EClass{Analysis}(id, VecExpr[copy(n)], Pair{VecExpr,Id}[], make(g, n))
   g.classes[IdKey(id)] = eclass
   modify!(g, eclass)
   push!(g.pending, n => id)
@@ -320,28 +302,22 @@ function addexpr!(g::EGraph, se)::Id
   se isa EClass && return se.id
   e = preprocess(se)
 
-  n = if isexpr(e)
-    args = iscall(e) ? arguments(e) : children(e)
-    ar = length(args)
-    n = v_new(ar)
-    v_set_flag!(n, VECEXPR_FLAG_ISTREE)
-    iscall(e) && v_set_flag!(n, VECEXPR_FLAG_ISCALL)
-
-    h = iscall(e) ? operation(e) : head(e)
-    v_set_head!(n, add_constant!(g, h))
-
-    # get the signature from op and arity 
-    v_set_signature!(n, hash(maybe_quote_operation(h), hash(ar)))
-
-    for i in v_children_range(n)
-      @inbounds n[i] = addexpr!(g, args[i - VECEXPR_META_LENGTH])
-    end
-    n
-  else # constant enode
-    VecExpr(Id[Id(0), Id(0), Id(0), add_constant!(g, e)])
+  isexpr(e) || return add!(g, VecExpr(Id[Id(0), Id(0), Id(0), add_constant!(g, e)]), false)
+
+  args = iscall(e) ? arguments(e) : children(e)
+  ar = length(args)
+  n = v_new(ar)
+  v_set_flag!(n, VECEXPR_FLAG_ISTREE)
+  iscall(e) && v_set_flag!(n, VECEXPR_FLAG_ISCALL)
+  h = iscall(e) ? operation(e) : head(e)
+  v_set_head!(n, add_constant!(g, h))
+  # get the signature from op and arity
+  v_set_signature!(n, hash(maybe_quote_operation(h), hash(ar)))
+  for i in v_children_range(n)
+    @inbounds n[i] = addexpr!(g, args[i - VECEXPR_META_LENGTH])
   end
-  id = add!(g, n, false)
-  return id
+
+  add!(g, n, false)
 end
 
 """
@@ -431,10 +407,10 @@ function process_unions!(g::EGraph{ExpressionType,AnalysisType})::Int where {Exp
   while !isempty(g.pending) || !isempty(g.analysis_pending)
     while !isempty(g.pending)
       (node::VecExpr, eclass_id::Id) = pop!(g.pending)
+      node = copy(node)
       canonicalize!(g, node)
-      if haskey(g.memo, node)
-        old_class_id = g.memo[node]
-        g.memo[node] = eclass_id
+      old_class_id = get!(g.memo, node, eclass_id)
+      if old_class_id != eclass_id
         did_something = union!(g, old_class_id, eclass_id)
         # TODO unique! can node dedup be moved here? compare performance
         # did_something && unique!(g[eclass_id].nodes)
@@ -474,9 +450,8 @@ function check_memo(g::EGraph)::Bool
   for (id, class) in g.classes
     @assert id.val == class.id
     for node in class.nodes
-      if haskey(test_memo, node)
-        old_id = test_memo[node]
-        test_memo[node] = id.val
+      old_id = get!(test_memo, node, id.val)
+      if old_id != id.val
         @assert find(g, old_id) == find(g, id.val) "Unexpected equivalence $node $(g[find(g, id.val)].nodes) $(g[find(g, old_id)].nodes)"
       end
     end
diff --git a/src/EGraphs/uniquequeue.jl b/src/EGraphs/uniquequeue.jl
index aade15d6..512bb61a 100644
--- a/src/EGraphs/uniquequeue.jl
+++ b/src/EGraphs/uniquequeue.jl
@@ -30,4 +30,4 @@ function Base.pop!(uq::UniqueQueue{T}) where {T}
   v
 end
 
-Base.isempty(uq::UniqueQueue) = isempty(uq.vec)
\ No newline at end of file
+Base.isempty(uq::UniqueQueue) = isempty(uq.vec)
diff --git a/src/vecexpr.jl b/src/vecexpr.jl
index 1e8a83ba..c18059f9 100644
--- a/src/vecexpr.jl
+++ b/src/vecexpr.jl
@@ -80,7 +80,7 @@ end
 
 """The hash of the e-node."""
 @inline v_hash(n::VecExpr)::Id = @inbounds n.data[1]
-Base.hash(n::VecExpr) = v_hash(n) # IdKey not necessary here
+Base.hash(n::VecExpr, h::UInt) = hash(v_hash(n), h) # IdKey not necessary here
 Base.:(==)(a::VecExpr, b::VecExpr) = (@view a.data[2:end]) == (@view b.data[2:end])
 
 """Set e-node hash to zero."""