diff --git a/src/SeapodymCohort.cpp b/src/SeapodymCohort.cpp
index e5506ce..72f767d 100755
--- a/src/SeapodymCohort.cpp
+++ b/src/SeapodymCohort.cpp
@@ -33,12 +33,12 @@ std::vector<double> SeapodymCohort::GetCohortDensity()
 void SeapodymCohort::InitializeCohort(dvar_vector& x, DistDataCollector& dataCollector, const bool writeoutputfiles) 
 {
 
-double t_all = MPI_Wtime();
-double t_rs = 0.0;
-double t_reset = MPI_Wtime();
-	//Reset model parameters:
-	reset(x);
-time_xreset += MPI_Wtime() - t_reset;	
+    double t_all = MPI_Wtime();
+    double t_rs = 0.0;
+    double t_reset = MPI_Wtime();
+    //Reset model parameters: moved to worker init in main_cohort.cpp
+    //reset(x);
+    time_xreset += MPI_Wtime() - t_reset;	
 
 	//----------------------------------------------//
 	//	ALLOCATE AND INITIALIZE COHORT DENSITY	//
diff --git a/src/main_cohort.cpp b/src/main_cohort.cpp
index 1c5920e..42f2824 100755
--- a/src/main_cohort.cpp
+++ b/src/main_cohort.cpp
@@ -17,6 +17,7 @@
 #include "Tags.h"
 #include <spdlog/spdlog.h>
 #include <spdlog/sinks/basic_file_sink.h>
+#include "admodel.h"
 
 double time_ic_comm = 0.0, time_ic_flush = 0.0, time_ic_copy = 0.0, time_spawning = 0.0, time_getdata = 0.0, time_xreset = 0.0, time_init_cohort_spawning = 0.0, time_init_cohort_restart = 0.0, time_io_forcing = 0.0;
 long   n_ic = 0;   // count of spawning-path inits, for per-init averages
@@ -56,7 +57,8 @@ SeapodymCohort xinit_prerun_wrapper(const char* parfile) {
 void taskFunction(int task_id, int stepBeg, int stepEnd, MPI_Comm comm,
 		const std::shared_ptr<spdlog::logger>& logger,
 		DistDataCollector* dataCollector,
-		SeapodymCohort* cohort){
+		SeapodymCohort* cohort,
+		const independent_variables& x){
 
 	static double last_task_end = -1.0;        // per-worker process, persists across calls
 	double t_in = MPI_Wtime();
@@ -68,11 +70,6 @@ void taskFunction(int task_id, int stepBeg, int stepEnd, MPI_Comm comm,
 	logger->info("> task id {} for steps {} to {}", task_id, stepBeg, stepEnd);
 
 	logger->info("    >> initialization of task id {}", task_id);
-	//initialize variables of optimization
-	const int nvar = cohort->nvarcalc();
-	independent_variables x(1, nvar);
-	adstring_array x_names(1,nvar);
-	cohort->xinit(x, x_names);
 
 	int cohort_id = task_id;
 	cohort->restart(cohort_id);
@@ -253,6 +250,14 @@ int main(int argc, char** argv) {
 
 			SeapodymCohort cohort= xinit_prerun_wrapper(parfile.c_str());
 
+			// Initialize optimization variables once; x is stable for all tasks
+			// (xinit fills x from fixed model parameters that don't change between tasks).
+			// x is captured by reference in taskFunc — lifetime matches the enclosing block.
+			const int nvar = cohort.nvarcalc();
+			independent_variables x(1, nvar);
+			adstring_array x_names(1, nvar);
+			cohort.xinit(x, x_names);
+
 			cohort.setDataProvider(&dp);
 
 			//MPI_Win_fence(0, dp.win());
@@ -261,6 +266,11 @@ int main(int argc, char** argv) {
 			//MPI_Win_fence(0, dp.win());
 			double t_shm = MPI_Wtime();
 			cohort.setShmForcing();          // every node-local worker reads its timestep slice
+
+			// Reset model parameters (applies boundp() transforms from optimisation space to
+			// physical parameter space) — done once here rather than per-task in InitializeCohort.
+			cohort.reset(dvar_vector(x));
+
 			MPI_Barrier(dp.getShmComm());    // per-node publish-sync: all slabs visible before any read
 
 			time_io_forcing += MPI_Wtime()-t_shm;
@@ -272,7 +282,8 @@ int main(int argc, char** argv) {
 				std::placeholders::_4, // MPI communicator so we can send messages to the manager at the end of each step
 				logger,
 				&dataCollect,
-				&cohort);
+				&cohort,
+				std::cref(x));        // x lives in this block, outlives taskFunc and worker.run()
 
 			TaskStepWorker worker(MPI_COMM_WORLD, taskFunc, stepBegMap, stepEndMap);