This really depends on the specific application, so it's really hard to say in general. However, I would be pretty surprised if object creation was actually a performance bottleneck in an application. Even if they are slow, the code-style benefit will probably outweigh the performance (unless it's actually noticeable to the user)
In any case, you shouldn't even start to worry about these things until you have profiled your code to determine the actual performance bottlenecks instead of guessing. Until then, you should do whatever is best for code readability, not performance.
