When using OzRunways make sure you have shut down all the other programmes. Even though they are asleep in the background some, use a lot more resources than others.
When your iThingie gets short of memory it signals the foreground app to reduce memory usage. If it is still short of memory it then kills background apps (starting at the biggest) until there is enough free memory. If there is still not enough memory then the foreground app is also killed.
Manually killing background apps wont make a difference - they will be killed anyway, to keep the foreground app running.
You will still see these killed background apps in the task switcher though. If you press on them a killed background app will do a full restart. Its just fooling you into thinking that they are still running.
The joys of coding on a memory constrained device...
Bevan..