diff --git a/CMakeLists.txt b/CMakeLists.txt
index d59eb3e..0b4d0fd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(blt-gp VERSION 0.0.68)
+project(blt-gp VERSION 0.0.69)
 
 include(CTest)
 
diff --git a/examples/pg_symbolic_regression.cpp b/examples/pg_symbolic_regression.cpp
index df5424c..5ecf031 100644
--- a/examples/pg_symbolic_regression.cpp
+++ b/examples/pg_symbolic_regression.cpp
@@ -36,8 +36,8 @@ blt::gp::prog_config_t config = blt::gp::prog_config_t()
         .set_initial_max_tree_size(6)
         .set_elite_count(0)
         .set_max_generations(50)
-        .set_pop_size(5000)
-        .set_thread_count(0);
+        .set_pop_size(500)
+        .set_thread_count(1);
 
 blt::gp::type_provider type_system;
 blt::gp::gp_program program{type_system, SEED, config};
diff --git a/include/blt/gp/program.h b/include/blt/gp/program.h
index b34b8d2..ac788fb 100644
--- a/include/blt/gp/program.h
+++ b/include/blt/gp/program.h
@@ -286,9 +286,16 @@ namespace blt::gp
                 if (config.threads == 1)
                 {
                     thread_execution_service = new std::function([this, &fitness_function]() {
-                        if (thread_helper.evaluation_left > 0)
+                        for (const auto& ind : blt::enumerate(current_pop.get_individuals()))
                         {
-                        
+                            fitness_function(ind.second.tree, ind.second.fitness, ind.first);
+                            if (ind.second.fitness.adjusted_fitness > current_stats.best_fitness)
+                                current_stats.best_fitness = ind.second.fitness.adjusted_fitness;
+                            
+                            if (ind.second.fitness.adjusted_fitness < current_stats.worst_fitness)
+                                current_stats.worst_fitness = ind.second.fitness.adjusted_fitness;
+                            
+                            current_stats.overall_fitness = current_stats.overall_fitness + ind.second.fitness.adjusted_fitness;
                         }
                     });
                 } else
diff --git a/include/blt/gp/stack.h b/include/blt/gp/stack.h
index 297f859..d119694 100644
--- a/include/blt/gp/stack.h
+++ b/include/blt/gp/stack.h
@@ -401,11 +401,12 @@ namespace blt::gp
                 auto old = head;
                 head = head->metadata.prev;
                 if (head == nullptr)
-                    free_chain(old);
+                    head = old;
+                    //free_chain(old);
                 // required to prevent silly memory :3
-                //if (head != nullptr)
-                //    head->metadata.next = nullptr;
-                //std::free(old);
+//                if (head != nullptr)
+//                    head->metadata.next = nullptr;
+//                std::free(old);
             }
         
         private:
diff --git a/test_perf.sh b/test_perf.sh
index 075b123..7ace957 100755
--- a/test_perf.sh
+++ b/test_perf.sh
@@ -1 +1 @@
-perf stat -d -d -d -r 30 -e branches,branch-misses,cache-misses,cache-references,cycles,instructions,alignment-faults,cgroup-switches,faults,duration_time,user_time,system_time,L1-dcache-loads,L1-dcache-load-misses,L1-dcache-prefetches,L1-icache-loads,L1-icache-load-misses,dTLB-loads,dTLB-load-misses,iTLB-loads,iTLB-load-misses,l2_request_g1.all_no_prefetch ./cmake-build-release/blt-SR-playground-example
+perf stat -d -d -d -r 30 -e branches,branch-misses,cache-misses,cache-references,cycles,instructions,alignment-faults,cgroup-switches,faults,duration_time,user_time,system_time,L1-dcache-loads,L1-dcache-load-misses,L1-dcache-prefetches,L1-icache-loads,L1-icache-load-misses,dTLB-loads,dTLB-load-misses,iTLB-loads,iTLB-load-misses,l2_request_g1.all_no_prefetch,page-faults,page-faults:u,page-faults:k ./cmake-build-release/blt-SR-playground-example