diff --git a/CMakeLists.txt b/CMakeLists.txt
index a462d59..7c70c89 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.2)
 message(STATUS "Cmake version ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION}")
 project(task_clustering_batch_simulator)
 add_definitions("-Wall -Wno-unused-variable -Wno-unused-private-field")
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_BUILD_TYPE release)
 
 
diff --git a/src/Util/WorkflowUtil.cpp b/src/Util/WorkflowUtil.cpp
index fb938a4..378496d 100644
--- a/src/Util/WorkflowUtil.cpp
+++ b/src/Util/WorkflowUtil.cpp
@@ -16,6 +16,7 @@
 #ifdef PRINT_RAM_MACOSX
 #include<mach/mach.h>
 #endif
+#include <unordered_map>
 
 #include "WorkflowUtil.h"
 
@@ -24,6 +25,8 @@ XBT_LOG_NEW_DEFAULT_CATEGORY(workflow_util, "Log category for Workflow Util");
 
 namespace wrench {
 
+std::unordered_map<WorkflowTask*, std::vector<WorkflowTask*>> lineage;
+
 #ifdef PRINT_RAM_MACOSX
     void WorkflowUtil::printRAM() {
 
@@ -56,6 +59,14 @@ namespace wrench {
     double WorkflowUtil::estimateMakespan(std::vector<WorkflowTask *> tasks,
                                           unsigned long num_hosts, double core_speed) {
 
+        if (lineage.empty()) {
+            auto workflow = (*tasks.begin())->getWorkflow();
+            for (auto task : workflow->getTasks()) {
+                std::vector<WorkflowTask *> parents = task->getParents();
+                lineage[task] = parents;
+            }
+        }
+
         if (num_hosts == 0) {
             throw std::runtime_error("Cannot estimate makespan with 0 hosts!");
         }
@@ -113,7 +124,7 @@ namespace wrench {
 
                 // Determine whether the task is schedulable
                 bool schedulable = true;
-                for (auto parent : workflow->getTaskParents(real_task)) {
+                for (auto parent : lineage[real_task]) {
                     if ((fake_tasks[parent] > current_time) or
                         (fake_tasks[parent] < 0)) {
                         schedulable = false;