Merge pull request #198 from blaues0cke/patch-2

Fixed a typo in "performance"

Author: Simperfit

core/performance.md

@@ -22,7 +22,7 @@ Keep in mind that PPM is still in an early stage of development and can cause is
 
 When using the `SearchFilter` and case insensivity, Doctrine will use the `LOWER` SQL function. Depending on your
 driver, you may want to carefully index it by using a [function-based
-index](http://use-the-index-luke.com/sql/where-clause/functions/case-insensitive-search) or it will impact performanc
+index](http://use-the-index-luke.com/sql/where-clause/functions/case-insensitive-search) or it will impact performance
 with a huge collection. [Here are some examples to index LIKE
 filters](http://use-the-index-luke.com/sql/where-clause/searching-for-ranges/like-performance-tuning) depending on your
 database driver.