diff --git a/collector/src/main/java/io/prometheus/jmx/JmxCollector.java b/collector/src/main/java/io/prometheus/jmx/JmxCollector.java
index 567f12f05..fbe685127 100644
--- a/collector/src/main/java/io/prometheus/jmx/JmxCollector.java
+++ b/collector/src/main/java/io/prometheus/jmx/JmxCollector.java
@@ -476,7 +476,12 @@ private MatchedRule defaultExport(
                 Double value,
                 double valueFactor,
                 String type) {
-            StringBuilder name = new StringBuilder();
+            // avoid having to grow the StringBuilder incrementally, by calculating its capacity up-front
+            int estimatedSize = domain.length() +
+                    (beanProperties.isEmpty() ? 0 : 1 + beanProperties.values().iterator().next().length()) +
+                    (attrKeys.stream().map(k -> k.length() + 1).reduce(0, Integer::sum)) +
+                    attrName.length() + 1;
+            StringBuilder name = new StringBuilder(estimatedSize);
             name.append(domain);
             if (beanProperties.size() > 0) {
                 name.append(SEP);