5 minute load times could be excessively bloated FSX or a not-to-well optimized system.
Due to recent "issues" I had to do a fresh FSX install. I was amazed to be at the menu in about 35 seconds and in the air in less than a minute from "Fly Now".
A fresh install of UTX extended the load flight time only slightly so I've added back Ultimate traffic, custom traffic, a few scenery addons and only a few of my favorite addon AC so now I'm up to about 75/90 seconds, depending on location and scenery detail levels etc...
As we add more scenery and more aircraft and more traffic the times will necessarily go up because FSX has to parse through all of that stuff.
I think most folks agree that using a GOOD defragging utility will have a very big impact on load times - I use Ultimate Defrag and have positioned all of FSX in a block at the beginning of a drive. My pagefile is a fixed 4G but I've never seen more than 2G in use.
Another thing that makes a big impact is other processes running at the same time. Opening up the Windows Task manager before starting FSX will tell how many other processes are already running (I have 38 at the moment). If you are well above this range, it will probably help to shut some of them down.
I'm expecting noticeable improvement when I move up to the new generation of hardware in a few months. Single-core is 'ok' for my VFR style flying but I do like the eye-candy and enhanced environment.
Hooked since FS4... now flying: FSX Acceleration on Win7/64, Core Duo E8400; GA-EP45-DS3R; GTX 460-768MB; 4G RAM; Freezer 7 Pro