diff --git a/gson/src/main/java/com/google/gson/internal/bind/EnumTypeAdapter.java b/gson/src/main/java/com/google/gson/internal/bind/EnumTypeAdapter.java
index 5f24dc18d9..b3dbb680c1 100644
--- a/gson/src/main/java/com/google/gson/internal/bind/EnumTypeAdapter.java
+++ b/gson/src/main/java/com/google/gson/internal/bind/EnumTypeAdapter.java
@@ -50,9 +50,16 @@ public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
         }
       };
 
-  private final Map<String, T> nameToConstant = new HashMap<>();
-  private final Map<String, T> stringToConstant = new HashMap<>();
-  private final Map<T, String> constantToName = new HashMap<>();
+  /**
+   * Taken from Java 19 method {@link HashMap.newHashMap}, using default load factor {@code 0.75F}.
+   */
+  private static int calculateHashMapCapacity(int numMappings) {
+    return (int) Math.ceil(numMappings / 0.75F);
+  }
+
+  private final Map<String, T> nameToConstant;
+  private final Map<String, T> stringToConstant;
+  private final Map<T, String> constantToName;
 
   private EnumTypeAdapter(Class<T> classOfT) {
     try {
@@ -71,6 +78,12 @@ private EnumTypeAdapter(Class<T> classOfT) {
       // one declared field which is not an enum constant, namely the implicit $VALUES array
       fields = Arrays.copyOf(fields, constantCount);
 
+      int hashMapCapacity = calculateHashMapCapacity(constantCount);
+      nameToConstant = new HashMap<>(hashMapCapacity);
+      stringToConstant = new HashMap<>(hashMapCapacity);
+      // Don't use `EnumMap` here; that can break when using ProGuard or R8
+      constantToName = new HashMap<>(hashMapCapacity);
+
       AccessibleObject.setAccessible(fields, true);
 
       for (Field constantField : fields) {