diff --git a/flow/scripts/report_metrics.tcl b/flow/scripts/report_metrics.tcl
index 7c635598e3..d0af3e97af 100644
--- a/flow/scripts/report_metrics.tcl
+++ b/flow/scripts/report_metrics.tcl
@@ -31,7 +31,7 @@ proc report_metrics { stage when {include_erc true} {include_clock_skew true} }
   report_worst_slack >> $filename
   report_worst_slack_metric >> $filename
 
-  if {$include_clock_skew} {
+  if {$include_clock_skew && $::env(REPORT_CLOCK_SKEW)} {
     report_puts "\n=========================================================================="
     report_puts "$when report_clock_skew"
     report_puts "--------------------------------------------------------------------------"
diff --git a/flow/scripts/variables.yaml b/flow/scripts/variables.yaml
index ec9f36c5ad..52ae158e77 100644
--- a/flow/scripts/variables.yaml
+++ b/flow/scripts/variables.yaml
@@ -81,6 +81,18 @@ CORE_AREA:
     (X1 Y1 X2 Y2).
   stages:
     - floorplan
+REPORT_CLOCK_SKEW:
+  description:
+    Report clock skew as part of reporting metrics, starting at CTS,
+    before which there is no clock skew.
+
+    This metric can be quite time-consuming, so it can be useful to disable.
+  stages:
+    - cts
+    - grt
+    - route
+    - final
+  default: 1
 SKIP_REPORT_METRICS:
   description: >
     If set to 1, then metrics, report_metrics does nothing. Useful to speed up builds.