Java Pitfalls - Performance Issues
Pitfall - String concatenation in a loop does not scale
Pitfall - Using size to test if a collection is empty is inefficient.
Pitfall - Using new to create primitive wrapper instances is inefficient
Pitfall - Interning strings so that you can use is a bad idea
Pitfall - Efficiency concerns with regular expressions
Pitfall - Small reads writes on unbuffered streams are inefficient
Pitfall - Over-use of primitive wrapper types is inefficient
Pitfall - Iterating a Maps keys can be inefficient
Pitfall - The overheads of creating log messages