diff --git a/src/GLWidget.cpp b/src/GLWidget.cpp
index c5b5ca7..c46b66c 100644
--- a/src/GLWidget.cpp
+++ b/src/GLWidget.cpp
@@ -9,6 +9,7 @@
 #include "Overlay.h"
 #include <QOpenGLShaderProgram>
 #include "FPS.h"
+#include "Pendulum.h"
 
 GLWidget::GLWidget(Simulation * simulation) : simulation(simulation) {
 	startTimer(1000 / 144);
@@ -186,6 +187,7 @@ void GLWidget::uploadStaticDataToGPU() {
 }
 
 void GLWidget::changePosition() {
+	auto t1 = system_clock::now();
 	glBindBuffer(GL_ARRAY_BUFFER, positionVBO);
 	auto positions = (GLfloat*) glMapBufferRange(GL_ARRAY_BUFFER, 0, GLsizeiptr(positionCount * sizeof(float)), GL_MAP_WRITE_BIT);
 	size_t index = 0;
@@ -198,6 +200,7 @@ void GLWidget::changePosition() {
 		}
 	}
 	glUnmapBuffer(GL_ARRAY_BUFFER);
+	// std::cout << duration_cast<microseconds>(system_clock::now() - t1).count() << std::endl;
 	simulation->semaphore.release();
 }
 
diff --git a/src/MainWindow.cpp b/src/MainWindow.cpp
index 7105cb6..3abe412 100644
--- a/src/MainWindow.cpp
+++ b/src/MainWindow.cpp
@@ -17,6 +17,7 @@
 #include <QCloseEvent>
 #include <QTimer>
 #include "Overlay.h"
+#include "Slider.h"
 
 MainWindow::MainWindow() {
 	simulationThread = new QThread(this);
diff --git a/src/MainWindow.h b/src/MainWindow.h
index b61bc53..c69fcdd 100644
--- a/src/MainWindow.h
+++ b/src/MainWindow.h
@@ -1,11 +1,12 @@
 #include <QWidget>
 #include <vector>
-#include "Slider.h"
 #include "Pendulum.h"
 
 class Simulation;
 class QGridLayout;
 class GLWidget;
+template<typename T>
+		class Slider;
 
 enum Property {Angle, Mass, Length};
 
@@ -38,7 +39,7 @@ private:
 
 	QGridLayout * segmentGrid {};
 	Slider<double> * gravitySlider = nullptr, * timescaleSlider = nullptr;
-	Slider<> * substepsSlider = nullptr;
+	Slider<int> * substepsSlider = nullptr;
 
 signals:
 	void pendulaCreated(const std::vector<Pendulum*> &add);
diff --git a/src/Simulation.cpp b/src/Simulation.cpp
index 2a234e0..86ebab4 100644
--- a/src/Simulation.cpp
+++ b/src/Simulation.cpp
@@ -5,6 +5,7 @@
 #include <omp.h>
 #include <iostream>
 #include "FPS.h"
+#include "Pendulum.h"
 #include <QOpenGLContext>
 #include <QOpenGLShaderProgram>
 #include <QOffscreenSurface>
@@ -12,7 +13,6 @@
 Simulation::Simulation() {
 	ups = new FPS;
 	ups->setUpdateInterval(100);
-
 	timer = new QTimer(this);
 	QTimer::connect(timer, &QTimer::timeout, this, &Simulation::update);
 	timer->setInterval(updateInterval);
@@ -33,19 +33,23 @@ void Simulation::initialize() {
 		initializeOpenGLFunctions();
 	}
 
-	int maxWorkGroupCount[3];
-	int maxWorkGroupSize[3];
-	int maxWorkGroupInvocations;
-	for (int i = 0; i < 3; i++){
-		glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT, i, maxWorkGroupCount + i);
-		glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE, i, maxWorkGroupSize + i);
+	// Read GPU Limits
+	{
+		for (int i = 0; i < 3; i++){
+			glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT, i, gpuLimits.maxWGCount + i);
+			glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE, i, gpuLimits.maxWGSize + i);
+		}
+		glGetIntegerv(GL_MAX_COMPUTE_WORK_GROUP_INVOCATIONS, &gpuLimits.maxWGInvocations);
+
+		printf("Max work group count: (%d, %d, %d)\n", gpuLimits.maxWGCount[0], gpuLimits.maxWGCount[1], gpuLimits.maxWGCount[2]);
+		printf("Max work group size: (%d, %d, %d)\n", gpuLimits.maxWGSize[0], gpuLimits.maxWGSize[1], gpuLimits.maxWGSize[2]);
+		printf("Max work group invocations (x * y * z): %d\n", gpuLimits.maxWGInvocations);
 	}
-	glGetIntegerv(GL_MAX_COMPUTE_WORK_GROUP_INVOCATIONS, &maxWorkGroupInvocations);
 
+	// Shader
+	{
 
-	printf("Max work group count: (%d, %d, %d)\n", maxWorkGroupCount[0], maxWorkGroupCount[1], maxWorkGroupCount[2]);
-	printf("Max work group size: (%d, %d, %d)\n", maxWorkGroupSize[0], maxWorkGroupSize[1], maxWorkGroupSize[2]);
-	printf("Max work group invocations (x * y * z): %d\n", maxWorkGroupInvocations);
+	}
 
 }
 
@@ -62,18 +66,30 @@ void Simulation::update() {
 	double newPotentialEnergy = 0;
 	double newKineticEnergy = 0;
 
-	#pragma omp parallel for
-	for (int i = 0; i < pendula.size(); i++){ // NOLINT(*-loop-convert) // not ranged based for msvc
-		for (int k = 0; k < substeps; k++)
-			pendula[i]->update(h, gravity);
-		double localPotentialEnergy = pendula[i]->potentialEnergy(gravity);
-		double localKineticEnergy = pendula[i]->kineticEnergy();
-		#pragma omp atomic
-		newPotentialEnergy += localPotentialEnergy;
-		#pragma omp atomic
-		newKineticEnergy += localKineticEnergy;
+
+
+	// OLD with CPUs
+	{
+
+		#pragma omp parallel for
+		for (int i = 0; i < pendula.size(); i++){ // NOLINT(*-loop-convert) // not ranged based for msvc
+			for (int k = 0; k < substeps; k++)
+				pendula[i]->update(h, gravity);
+			double localPotentialEnergy = pendula[i]->potentialEnergy(gravity);
+			double localKineticEnergy = pendula[i]->kineticEnergy();
+			#pragma omp atomic
+			newPotentialEnergy += localPotentialEnergy;
+			#pragma omp atomic
+			newKineticEnergy += localKineticEnergy;
+		}
 	}
 
+	// NEW with GPUs
+	{
+
+	}
+
+
 	potentialEnergy = newPotentialEnergy;
 	kineticEnergy = newKineticEnergy;
 
@@ -92,6 +108,7 @@ void Simulation::clearPendula() {
 	pendula.shrink_to_fit();
 
 	updateEnergy();
+	updateGPUData();
 
 	emit layoutChanged();
 }
@@ -103,6 +120,7 @@ void Simulation::addPendula(const std::vector<Pendulum *> &add) {
 		pendula.push_back(p);
 
 	updateEnergy();
+	updateGPUData();
 
 	emit layoutChanged();
 }
@@ -115,3 +133,7 @@ void Simulation::updateEnergy() {
 	}
 }
 
+void Simulation::updateGPUData() {
+
+}
+
diff --git a/src/Simulation.h b/src/Simulation.h
index c106e13..726da3f 100644
--- a/src/Simulation.h
+++ b/src/Simulation.h
@@ -2,12 +2,12 @@
 #include <cstdint>
 #include <QObject>
 #include <chrono>
-#include "Pendulum.h"
 #include <semaphore>
 #include <QOpenGLFunctions_4_3_Core>
 
-class QTimer;
 class FPS;
+class Pendulum;
+class QOpenGLShaderProgram;
 
 class Simulation : public QObject, protected QOpenGLFunctions_4_3_Core {
 	Q_OBJECT
@@ -40,6 +40,13 @@ public slots:
 private slots:
 	void update();
 private:
+	void updateGPUData();
+	struct GPULimits {
+		int maxWGCount[3];
+		int maxWGSize[3];
+		int maxWGInvocations;
+	} gpuLimits;
+	QOpenGLShaderProgram * program;
 	QTimer * timer;
 	int updateInterval = 16;
 };
\ No newline at end of file
diff --git a/src/Slider.h b/src/Slider.h
index 2fcc80b..873c0ab 100644
--- a/src/Slider.h
+++ b/src/Slider.h
@@ -1,3 +1,5 @@
+#pragma once
+
 #include <QSlider>
 #include <functional>
 #include <QLabel>