diff --git a/src/core/algorithms/generative.jl b/src/core/algorithms/generative.jl
index a96a8f8..5c6c643 100644
--- a/src/core/algorithms/generative.jl
+++ b/src/core/algorithms/generative.jl
@@ -20,18 +20,22 @@ a function that takes a node, and returns a Vector{<:BranchModel} if you need th
 partition_list (eg. 1:3 or [1,3,5]) lets you choose which partitions to run over.
 """
 function sample_down!(node::FelNode, models, partition_list)
-    model_list = models(node)
-    for part in partition_list
-        if isroot(node)
-            forward!(node.message[part], node.parent_message[part], model_list[part], node)
-        else
-            forward!(node.message[part], node.parent.message[part], model_list[part], node) #node.parent['.' vs. '_']message[part]
+    stack = [node]
+    while !isempty(stack)
+        node = pop!(stack)
+        model_list = models(node)
+        for part in partition_list
+            if isroot(node)
+                forward!(node.message[part], node.parent_message[part], model_list[part], node)
+            else
+                forward!(node.message[part], node.parent.message[part], model_list[part], node) #node.parent['.' vs. '_']message[part]
+            end
+            sample_partition!(node.message[part])
         end
-        sample_partition!(node.message[part])
-    end
-    if !isleafnode(node)
-        for child in node.children
-            sample_down!(child, models, partition_list)
+        if !isleafnode(node)
+            for child in reverse(node.children) #We push! in reverse order because of LazyPartition, so that lazysort! is optimal for both felsenstein! and sample_down!
+                push!(stack, child)
+            end
         end
     end
 end
diff --git a/src/core/nodes/AbstractTreeNode.jl b/src/core/nodes/AbstractTreeNode.jl
index 82f29f3..072916e 100644
--- a/src/core/nodes/AbstractTreeNode.jl
+++ b/src/core/nodes/AbstractTreeNode.jl
@@ -347,10 +347,15 @@ function prettyprintstring(node::T, spaces::Int = 0) where {T<:AbstractTreeNode}
 end
 
 export getnodelist
-function getnodelist(node::T, nodelist::Array{T,1} = T[]) where {T<:AbstractTreeNode}
-    push!(nodelist, node)
-    for childnode in node.children #Fixing this to avoid implementing iterate(::FelNode)
-        getnodelist(childnode, nodelist)
+function getnodelist(node::T) where {T<:AbstractTreeNode}
+    nodelist = []
+    nodes = [node]
+    while nodes != []
+        node = pop!(nodes)
+        push!(nodelist, node)
+        for child in node.children
+            push!(nodes, child)
+        end
     end
     return nodelist
 end
@@ -385,23 +390,34 @@ function treedepth(node::T) where {T<:AbstractTreeNode}
 end
 
 export getnonleaflist
-function getnonleaflist(node::T, nonleaflist::Array{T,1} = T[]) where {T<:AbstractTreeNode}
-    if !isleafnode(node)
-        push!(nonleaflist, node)
-    end
-    for childnode in node.children
-        getnonleaflist(childnode, nonleaflist)
+function getnonleaflist(node::T) where {T<:AbstractTreeNode}
+    nonleaflist = []
+    nodes = [node]
+    while nodes != []
+        node = pop!(nodes)
+        if node.children != []
+            push!(nonleaflist, node)
+            for child in node.children
+                push!(nodes, child)
+            end
+        end
     end
     return nonleaflist
 end
 
 export getleaflist
-function getleaflist(node::T, leaflist::Array{T,1} = T[]) where {T<:AbstractTreeNode}
-    if isleafnode(node)
-        push!(leaflist, node)
-    end
-    for childnode in node.children
-        getleaflist(childnode, leaflist)
+function getleaflist(node::T) where {T<:AbstractTreeNode}
+    leaflist = []
+    nodes = [node]
+    while nodes != []
+        node = pop!(nodes)
+        if node.children == []
+            push!(leaflist, node)
+        else 
+            for child in node.children
+                push!(nodes, child)
+            end
+        end
     end
     return leaflist
 end
@@ -432,16 +448,45 @@ function ladderize(tree::T) where {T<:AbstractTreeNode}
 end
 
 function ladderize!(tree::T) where {T<:AbstractTreeNode}
+    child_counts = countchildren(tree)
     for node in getnodelist(tree)
-        if length(node.children) != 0
-            sort!(
-                node.children,
-                lt = (x, y) -> length(getnodelist(x)) < length(getnodelist(y)),
-            )
+        if !isempty(node.children)
+            sort!(node.children, lt = (x, y) -> child_counts[x] < child_counts[y])
         end
     end
 end
 
+# Creates a dictionary of all the child counts (including the node itself) which can then be used by ladderize to sort the nodes
+function countchildren(tree::T) where {T<:AbstractTreeNode}
+    # Initialize the dictionary to store the number of children for each node
+    children_count = Dict{T, Int}()
+
+    # Initialize the stack for DFS
+    stack = [tree]
+    
+    # Initialize a list to keep track of the post-order traversal
+    post_order = []
+
+    # First pass: Perform DFS and store the nodes in post-order
+    while !isempty(stack)
+       node = pop!(stack)
+       push!(post_order, node)
+       for child in node.children
+           push!(stack, child)
+       end
+    end
+
+    # Second pass: Calculate the number of children for each node in post-order
+    for node in reverse(post_order)
+       count = 0
+       for child in node.children
+           count += 1 + children_count[child]
+       end
+       children_count[node] = count
+    end
+
+   return children_count
+end
 
 function getorder(tree::T) where {T<:AbstractTreeNode}
     return [node.seqindex for node in getleaflist(tree)]