[Trivial] Add a comment on the use of prevector in script.

random-zebra · random-zebra · commit bdd98e87af3a · 2020-05-17T15:19:34.000+02:00
backports bitcoin/bitcoin@08f71c2
diff --git a/src/script/script.h b/src/script/script.h
@@ -363,6 +363,12 @@ class CScriptNum
     int64_t m_value;
 };
 
+/**
+ * We use a prevector for the script to reduce the considerable memory overhead
+ * of vectors in cases where they normally contain a small number of small elements.
+ * Tests in October 2015 (bitcoin) showed use of this reduced dbcache memory usage by 23%
+ *  and made an initial sync 13% faster.
+ */
 typedef prevector<28, unsigned char> CScriptBase;
 
 /** Serialized script, used inside transaction inputs and outputs */
