I have a site that receives 5 million request per day. On heavy days, the pages take about 10 seconds to return. I also get out of memory exceptions. I\'ve been reading the Impr
You don't give any indications as to where the potential problem is, so start with the basics mentioned by @Shiraz. There are performance counters you can dig into that should give you an indication as to where the problem is.
Once you've narrowed it down to a particular area, you can then dig in a bit deeper to see if it's a coding issue, or a hardware issue.
But there's not going to be a magic "watch this" to solve your problem. Solving scalability problems is hard.