diff --git a/CMakeLists.txt b/CMakeLists.txt
index e3e9fe7..2a27092 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(blt-gp VERSION 0.1.46)
+project(blt-gp VERSION 0.1.47)
 
 include(CTest)
 
diff --git a/examples/symbolic_regression.cpp b/examples/symbolic_regression.cpp
index 206bd8a..5c1c33f 100644
--- a/examples/symbolic_regression.cpp
+++ b/examples/symbolic_regression.cpp
@@ -39,12 +39,12 @@ blt::gp::mutation_t mut;
 blt::gp::prog_config_t config = blt::gp::prog_config_t()
         .set_initial_min_tree_size(2)
         .set_initial_max_tree_size(6)
-        .set_elite_count(200)
+        .set_elite_count(2)
         .set_crossover_chance(0.9)
         .set_mutation_chance(0.1)
         .set_reproduction_chance(0)
         .set_max_generations(50)
-        .set_pop_size(20000)
+        .set_pop_size(500)
         .set_thread_count(0);
 
 blt::gp::gp_program program{SEED, config};
@@ -65,7 +65,7 @@ constexpr auto fitness_function = [](blt::gp::tree_t& current_tree, blt::gp::fit
         if (diff < value_cutoff)
         {
             fitness.raw_fitness += diff;
-            if (diff < 0.01)
+            if (diff <= 0.01)
                 fitness.hits++;
         } else
             fitness.raw_fitness += value_cutoff;
@@ -99,7 +99,7 @@ int main()
     program.set_operations(builder.build(add, sub, mul, pro_div, op_sin, op_cos, op_exp, op_log, lit, op_x));
     
     BLT_DEBUG("Generate Initial Population");
-    auto sel = blt::gp::select_tournament_t{};
+    auto sel = blt::gp::select_fitness_proportionate_t{};
     program.generate_population(program.get_typesystem().get_type<float>().id(), fitness_function, sel, sel, sel);
     
     BLT_DEBUG("Begin Generation Loop");
diff --git a/include/blt/gp/selection.h b/include/blt/gp/selection.h
index 7c4c67b..e9c9b28 100644
--- a/include/blt/gp/selection.h
+++ b/include/blt/gp/selection.h
@@ -100,6 +100,8 @@ namespace blt::gp
                     {
                         p1 = &crossover_selection.select(program, current_pop);
                         p2 = &crossover_selection.select(program, current_pop);
+                        c1.copy_fast(*p1);
+                        c2->copy_fast(*p2);
                     } while (!config.crossover.get().apply(program, *p1, *p2, c1, *c2));
 #ifdef BLT_TRACK_ALLOCATIONS
                     tracker.stop_measurement_thread_local(state);
@@ -124,6 +126,7 @@ namespace blt::gp
                     do
                     {
                         p = &mutation_selection.select(program, current_pop);
+                        c1.copy_fast(*p);
                     } while (!config.mutator.get().apply(program, *p, c1));
 #ifdef BLT_TRACK_ALLOCATIONS
                     tracker.stop_measurement_thread_local(state);
@@ -144,7 +147,7 @@ namespace blt::gp
                     auto state = tracker.start_measurement_thread_local();
 #endif
                     // reproduction
-                    c1 = reproduction_selection.select(program, current_pop);
+                    c1.copy_fast(reproduction_selection.select(program, current_pop));
 #ifdef BLT_TRACK_ALLOCATIONS
                     tracker.stop_measurement_thread_local(state);
                     reproduction_calls.call();
diff --git a/include/blt/gp/typesystem.h b/include/blt/gp/typesystem.h
index 7c25ac1..20ec7ba 100644
--- a/include/blt/gp/typesystem.h
+++ b/include/blt/gp/typesystem.h
@@ -30,14 +30,14 @@
 
 namespace blt::gp
 {
-    struct operator_id : integer_type<blt::size_t>
+    struct operator_id : integer_type<blt::u64>
     {
-        using integer_type<blt::size_t>::integer_type;
+        using integer_type<blt::u64>::integer_type;
     };
     
-    struct type_id : integer_type<blt::size_t>
+    struct type_id : integer_type<blt::u64>
     {
-        using integer_type<blt::size_t>::integer_type;
+        using integer_type<blt::u64>::integer_type;
     };
     
     class type
diff --git a/src/transformers.cpp b/src/transformers.cpp
index 3f4e270..82693a2 100644
--- a/src/transformers.cpp
+++ b/src/transformers.cpp
@@ -61,9 +61,6 @@ namespace blt::gp
     
     bool crossover_t::apply(gp_program& program, const tree_t& p1, const tree_t& p2, tree_t& c1, tree_t& c2) // NOLINT
     {
-        c1.copy_fast(p1);
-        c2.copy_fast(p2);
-        
         auto& c1_ops = c1.get_operations();
         auto& c2_ops = c2.get_operations();
         
@@ -214,12 +211,9 @@ namespace blt::gp
         return crossover_point_t{static_cast<blt::ptrdiff_t>(crossover_point), static_cast<blt::ptrdiff_t>(attempted_point)};
     }
     
-    bool mutation_t::apply(gp_program& program, const tree_t& p, tree_t& c)
+    bool mutation_t::apply(gp_program& program, const tree_t&, tree_t& c)
     {
-        c.copy_fast(p);
-        
         mutate_point(program, c, program.get_random().get_size_t(0ul, c.get_operations().size()));
-        
         return true;
     }
     
@@ -307,9 +301,7 @@ namespace blt::gp
     
     bool advanced_mutation_t::apply(gp_program& program, const tree_t& p, tree_t& c)
     {
-        // child tree
-        c.copy_fast(p);
-        
+        (void) p;
         auto& ops = c.get_operations();
         auto& vals = c.get_values();