See Tux Run. Sit down and get comfortable as we continue to explore the pokes, prods and tweaks that affect old Tux's performance and, in some cases, simply how he does things.
Many different factors affect performance.
Changing one thing may or may not translate into a noticeable performance improvement. Sometimes, it's a question of a little tweaking here and a little tweaking there. Deciding what to change can be quite challenging. It also helps to be able to determine where the bottlenecks are. In particular, uptime tracks the load average, or number of processes waiting to be dealt with.