diff --git a/src/prevector.h b/src/prevector.h
--- a/src/prevector.h
+++ b/src/prevector.h
@@ -475,6 +475,12 @@
     iterator erase(iterator pos) { return erase(pos, pos + 1); }
 
     iterator erase(iterator first, iterator last) {
+        // Erase is not allowed to the change the object's capacity. That means
+        // that when starting with an indirectly allocated prevector with
+        // size and capacity > N, the result may be a still indirectly allocated
+        // prevector with size <= N and capacity > N. A shrink_to_fit() call is
+        // necessary to switch to the (more efficient) directly allocated
+        // representation (with capacity N and size <= N).
         iterator p = first;
         char *endp = (char *)&(*end());
         if (!std::is_trivially_destructible<T>::value) {
diff --git a/src/script/script.h b/src/script/script.h
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -653,8 +653,9 @@
     }
 
     void clear() {
-        // The default std::vector::clear() does not release memory.
-        CScriptBase().swap(*this);
+        // The default prevector::clear() does not release memory
+        CScriptBase::clear();
+        shrink_to_fit();
     }
 };