Ok, where to start...
If it's sat in memory and it's suspended; it can't freeze because it's suspended. So not sure where you're going with this. The memory that is used by these apps is similar to how Windows 7 marks memory as "Standby" memory. It's populated but you can take it if you need to without further ado; and the apps that used that memory are moved from the suspended state to the terminated state; but the icons are left on the recently used bar because that's not a multitasking bar; it's a bar to show recently used apps and is populated even after a restart unless you clear it.
Some applications don't use the correct API and might crash if they don't see enough memory left even though there is memory in this "Standby" kind of state. But that mainly happened under iOS 4.
Anyway; if you think that a suspended application can wake itself up, just to freeze: go ahead and delude yourself.
The only other rational explanation is that there is a hardware fault; and since this thread was concerned with the query of how to close apps quickly on an iPad; I addressed that concern in both how to do this and also reasoning why you shouldn't have to.
273 apps installed on my iPhone at present. I only restart once a month. I used to close apps but experimented not bothering. I've had no issues unless I don't close an app that remains open in the background like Mumble or Skype.
Farewell guys, removing these threads from my notifications as they're old and answered.