Here is an excellent howto for tuning buffer size. I have a Ubuntu installation with 2.6.30+ kernel. Are those changes required or will they boost performance on the kernel I have? I am asking this question because one of the comments on the howto page says kernels above 2.6.18 do not require such changes.
The stock kernel comes with settings that are not ideal for some environments. If you are transferring huge files over high throughput high latency connections you could probably benefit from some of the tuning advice in that page. Also if you are trying to host a service used by hundreds of thousands of users you may benefit as well. If the box is a small server doing minimal traffic it probably won't help much and the difference from the stock configuration could lead to other problems which may be difficult to diagnose.