fix javadocs

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_3x@1175526 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lucene/src/java/org/apache/lucene/index/IndexWriter.java b/lucene/src/java/org/apache/lucene/index/IndexWriter.java
index ad40b4d..c0b243b 100644
--- a/lucene/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/src/java/org/apache/lucene/index/IndexWriter.java
@@ -2399,7 +2399,7 @@
    * default merge policy, but individual merge policies may implement
    * optimize in different ways.
    *
-   * <p> Optimize is a fairly costly operation, so you
+   * <p> Optimize is a very costly operation, so you
    * should only do it if your search performance really
    * requires it.  Many search applications do fine never
    * calling optimize. </p>