diff --git a/src/grt/src/fastroute/include/FastRoute.h b/src/grt/src/fastroute/include/FastRoute.h
index 4fcbc973e1e..d22d1dd90a1 100644
--- a/src/grt/src/fastroute/include/FastRoute.h
+++ b/src/grt/src/fastroute/include/FastRoute.h
@@ -759,6 +759,8 @@ class FastRouteCore
   std::string congestion_file_name_;
   std::vector<odb::dbTechLayerDir> layer_directions_;
   std::vector<odb::dbTechLayer*> db_layers_;
+  double dbu_per_micron_ = 0.0;
+  std::vector<float> layer_res_per_micron_;
   int num_threads_;
   // When false, nets_ contains borrowed pointers from a parent
   // FastRouteCore (snapshot-batch workers).  Workers must not outlive
diff --git a/src/grt/src/fastroute/src/FastRoute.cpp b/src/grt/src/fastroute/src/FastRoute.cpp
index 47c50e18ac2..323bcf75f96 100644
--- a/src/grt/src/fastroute/src/FastRoute.cpp
+++ b/src/grt/src/fastroute/src/FastRoute.cpp
@@ -1330,6 +1330,8 @@ std::unique_ptr<FastRouteCore> FastRouteCore::buildSnapshotBatchWorker() const
   worker->congestion_file_name_ = congestion_file_name_;
   worker->layer_directions_ = layer_directions_;
   worker->db_layers_ = db_layers_;
+  worker->dbu_per_micron_ = dbu_per_micron_;
+  worker->layer_res_per_micron_ = layer_res_per_micron_;
   worker->en_estimate_parasitics_ = en_estimate_parasitics_;
   worker->resistance_aware_ = resistance_aware_;
   worker->enable_resistance_aware_ = enable_resistance_aware_;
diff --git a/src/grt/src/fastroute/src/utility.cpp b/src/grt/src/fastroute/src/utility.cpp
index 5a99a4336d8..acd47beae9d 100644
--- a/src/grt/src/fastroute/src/utility.cpp
+++ b/src/grt/src/fastroute/src/utility.cpp
@@ -519,11 +519,19 @@ void FastRouteCore::fixEdgeAssignment(int& net_layer,
 // Optimize performance
 void FastRouteCore::preProcessTechLayers()
 {
+  dbu_per_micron_
+      = db_->getChip()->getBlock()->getTech()->getDbUnitsPerMicron();
+  layer_res_per_micron_.assign(num_layers_, 0.0f);
+
   for (int layer = 0; layer < num_layers_; layer++) {
     odb::dbTech* tech = db_->getTech();
     odb::dbTechLayer* db_layer = tech->findRoutingLayer(layer + 1);
     db_layers_.emplace_back(db_layer);
 
+    // Keep layer_width as float: other rounding perturbs getWireCost() results
+    const float layer_width = dbuToMicrons(db_layer->getWidth());
+    layer_res_per_micron_[layer] = db_layer->getResistance() / layer_width;
+
     // Via
     db_layer = tech->findRoutingLayer(layer + 1)->getUpperLayer();
     db_layers_.emplace_back(db_layer);
@@ -543,25 +551,23 @@ float FastRouteCore::getWireResistance(const int layer,
                                        const int length,
                                        FrNet* net)
 {
-  odb::dbTechLayer* db_layer = getTechLayer(layer, false);
+  if (layer < net->getMinLayer() || layer > net->getMaxLayer()) {
+    return BIG_INT;
+  }
 
-  int width = db_layer->getWidth();
-  double resistance = db_layer->getResistance();
+  // Default-width value cached by preProcessTechLayers()
+  float res_ohm_per_micron = layer_res_per_micron_[layer];
 
   // If net has NDR, get the correct width value
   odb::dbTechNonDefaultRule* ndr = net->getDbNet()->getNonDefaultRule();
   if (ndr != nullptr) {
+    odb::dbTechLayer* db_layer = getTechLayer(layer, false);
     odb::dbTechLayerRule* layerRule = ndr->getLayerRule(db_layer);
-    width = layerRule->getWidth();
+    const float layer_width = dbuToMicrons(layerRule->getWidth());
+    res_ohm_per_micron = db_layer->getResistance() / layer_width;
   }
 
-  const float layer_width = dbuToMicrons(width);
-  const float res_ohm_per_micron = resistance / layer_width;
-  float final_resistance = res_ohm_per_micron * dbuToMicrons(length);
-
-  if (layer < net->getMinLayer() || layer > net->getMaxLayer()) {
-    return BIG_INT;
-  }
+  const float final_resistance = res_ohm_per_micron * dbuToMicrons(length);
 
   return final_resistance;
 }
@@ -2808,7 +2814,7 @@ odb::Rect FastRouteCore::globalRoutingToBox(const GSegment& route)
 
 double FastRouteCore::dbuToMicrons(const int dbu)
 {
-  return db_->getChip()->getBlock()->dbuToMicrons(dbu);
+  return dbu / dbu_per_micron_;
 }
 
 void FastRouteCore::saveCongestion(const int iter)