I'm curious what the impact on the server is when PHP if statements are evaluated, i.e. memory consumption and CPU usage and if this could become a major issue as traffic grows?

For example, if I use a lot of PHP IF statements in the theme for each post summary on a WordPress blog, is this going to require a great deal more server resources if the home page starts getting high traffic? And, on pages where many posts are listed (i.e. category pages) , it seems like this could become a problem.

I'm thinking it may be good idea to pare down the IF statements that aren't absolutely necessary in the event that traffic spikes. Or, is this even something I be worrying about?