diff --git a/lib/zone/store/base.js b/lib/zone/store/base.js
index 5df9f32..fc299b1 100644
--- a/lib/zone/store/base.js
+++ b/lib/zone/store/base.js
@@ -56,8 +56,11 @@ class ZoneBase {
 
 export default ZoneBase
 
+// A loop, as /\.+$/ backtracks quadratically over a run of dots mid-name
 export function canonicalZoneName(zone) {
-  return zone.replace(/\.+$/, '').toLowerCase()
+  let end = zone.length
+  while (end > 0 && zone[end - 1] === '.') end--
+  return zone.slice(0, end).toLowerCase()
 }
 
 export function withCanonicalZone(args) {