diff --git a/CMakeLists.txt b/CMakeLists.txt
index a89ee8b..f41377d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(blt-gp VERSION 0.1.25)
+project(blt-gp VERSION 0.1.26)
 
 include(CTest)
 
diff --git a/include/blt/gp/program.h b/include/blt/gp/program.h
index 5d7bfec..b86080f 100644
--- a/include/blt/gp/program.h
+++ b/include/blt/gp/program.h
@@ -123,7 +123,6 @@ namespace blt::gp
                     static thread_local evaluation_context results{};
                     results.values.reset();
                     results.values.reserve(largest);
-//                    BLT_DEBUG("%ld stored %ld", largest, results.values.internal_storage_size());
                     
                     blt::size_t total_so_far = 0;
                     
@@ -136,11 +135,6 @@ namespace blt::gp
                             continue;
                         }
                         call_jmp_table(operation.id, context, results.values, results.values, operators...);
-//                        if (results.values.internal_storage_size() != l)
-//                        {
-//                            BLT_DEBUG("Size %ld is now %ld", l, results.values.internal_storage_size());
-//                            l = results.values.internal_storage_size();
-//                        }
                     }
                     
                     return results;
@@ -507,22 +501,16 @@ namespace blt::gp
                                     while (thread_helper.next_gen_left > 0)
                                     {
                                         blt::size_t size = 0;
-                                        blt::size_t begin = 0;
                                         blt::size_t end = thread_helper.next_gen_left.load(std::memory_order_relaxed);
                                         do
                                         {
                                             size = std::min(end, config.evaluation_size);
-                                            begin = end - size;
                                         } while (!thread_helper.next_gen_left.compare_exchange_weak(end, end - size,
                                                                                                     std::memory_order::memory_order_relaxed,
                                                                                                     std::memory_order::memory_order_relaxed));
                                         
-                                        //auto measure = tracker.start_measurement();
-                                        for (blt::size_t i = begin; i < end; i++)
+                                        while (new_children.size() < size)
                                             func(args, crossover_selection, mutation_selection, reproduction_selection);
-                                        //tracker.stop_measurement(measure);
-                                        //BLT_TRACE("Allocated %ld times with a total of %s", measure.getAllocationDifference(),
-                                        //          blt::byte_convert_t(measure.getAllocatedByteDifference()).convert_to_nearest_type().to_pretty_string().c_str());
                                         
                                         {
                                             std::scoped_lock lock(thread_helper.thread_generation_lock);
@@ -553,6 +541,7 @@ namespace blt::gp
             
             void next_generation()
             {
+                BLT_ASSERT_MSG(next_pop.get_individuals().size() == config.population_size, ("pop size: " + std::to_string(next_pop.get_individuals().size())).c_str());
                 current_pop = std::move(next_pop);
                 current_generation++;
             }
diff --git a/include/blt/gp/selection.h b/include/blt/gp/selection.h
index 5c99354..baf4842 100644
--- a/include/blt/gp/selection.h
+++ b/include/blt/gp/selection.h
@@ -24,6 +24,7 @@
 #include <blt/gp/config.h>
 #include <blt/gp/random.h>
 #include <blt/std/assert.h>
+#include "blt/std/format.h"
 
 namespace blt::gp
 {
@@ -84,6 +85,7 @@ namespace blt::gp
                 // everyone gets a chance once per loop.
                 if (random.choice(config.crossover_chance))
                 {
+//                    auto state = tracker.start_measurement();
                     // crossover
                     auto& p1 = crossover_selection.select(program, current_pop, current_stats);
                     auto& p2 = crossover_selection.select(program, current_pop, current_stats);
@@ -94,24 +96,36 @@ namespace blt::gp
                     if (results)
                     {
                         next_pop.push_back(std::move(results->child1));
-                        next_pop.push_back(std::move(results->child2));
+                        if (next_pop.size() != config.population_size)
+                            next_pop.push_back(std::move(results->child2));
                     }
+//                    tracker.stop_measurement(state);
+//                    BLT_TRACE("Crossover Allocated %ld times with a total of %s", state.getAllocationDifference(),
+//                              blt::byte_convert_t(state.getAllocatedByteDifference()).convert_to_nearest_type().to_pretty_string().c_str());
                 }
                 break;
             case 1:
                 if (random.choice(config.mutation_chance))
                 {
+//                    auto state = tracker.start_measurement();
                     // mutation
                     auto& p = mutation_selection.select(program, current_pop, current_stats);
                     next_pop.push_back(std::move(config.mutator.get().apply(program, p)));
+//                    tracker.stop_measurement(state);
+//                    BLT_TRACE("Mutation Allocated %ld times with a total of %s", state.getAllocationDifference(),
+//                              blt::byte_convert_t(state.getAllocatedByteDifference()).convert_to_nearest_type().to_pretty_string().c_str());
                 }
                 break;
             case 2:
                 if (config.reproduction_chance > 0 && random.choice(config.reproduction_chance))
                 {
+//                    auto state = tracker.start_measurement();
                     // reproduction
                     auto& p = reproduction_selection.select(program, current_pop, current_stats);
                     next_pop.push_back(p);
+//                    tracker.stop_measurement(state);
+//                    BLT_TRACE("Reproduction Allocated %ld times with a total of %s", state.getAllocationDifference(),
+//                              blt::byte_convert_t(state.getAllocatedByteDifference()).convert_to_nearest_type().to_pretty_string().c_str());
                 }
                 break;
             default:
diff --git a/include/blt/gp/stack.h b/include/blt/gp/stack.h
index 4e6b62c..2ecb12c 100644
--- a/include/blt/gp/stack.h
+++ b/include/blt/gp/stack.h
@@ -121,7 +121,7 @@ namespace blt::gp
                 return getAllocatedBytes() - getDeallocatedBytes();
             }
             
-            allocation_data_t start_measurement()
+            [[nodiscard]] allocation_data_t start_measurement() const
             {
                 allocation_data_t data{};
                 data.start_allocations = allocations;
@@ -131,7 +131,7 @@ namespace blt::gp
                 return data;
             }
             
-            void stop_measurement(allocation_data_t& data)
+            void stop_measurement(allocation_data_t& data) const
             {
                 data.end_allocations = allocations;
                 data.end_deallocations = deallocations;