Optimizing IIS for peak performance

Long story short my web server that I have Essentials on is getting pounded by an IIS Worker Process with the name w3wp.exe and process model identity of NetworkService and it is eating up quite a bit of memory. My guess is that there may be a memory leak because that one process creeps up to a little over a gig of memory by mid day and will keep creeping unless I manually end the process. Our web adaptor, Essentials REST, Essentials REST Manager, wwwroot, and HTML5 viewer all have their own app pools under the NetworkService Identity (except wwwroot and HTML5 viewer are both in the same DefaultAppPool). If there is someone who has experience with configuring servers for optimal performance when it comes to memory usage that could give me some advice, I would greatly appreciate it.