FortiAP 423E High Memory Useage

Hello Guys, 

First Post, hopefully a genius knows the answer and it isn't too painful. 

I have a FortiAP 423E running 6.4 Build 0465 ( latest available ). 

It serves between 5-10 Clients at any one time so buy no means heavy, mix of 5GHz and 1 or 2 2.4GHz connections. 

From Boot, both FortiLAN Cloud and logging into the Device itself shows around 80% memory consumed. I've read some background scanning can cause high CPU and Memory on these so I disabled both scans and rebooted, same high issue. 

The CPU is very stable at low levels, which I would expect for the low User count but I can't figure out the memory. 

Does anyone have any experience of this, or any form of diagnostics I can do on AP's running without a FGT?

Thanks

Adam