calc freezes when saving

I have AMD quad core with 6gb ram. So where do i look to fix horrible saving time - about 45 seconds.
Have changed TOOLS>OPTIONS>MEMORY to 350mb but show TASK MANAGER nearly 1% usage & <2.5GB memory, and only spike during saving and returns to basic.
My document is <50mb with around 20 sheets with lots of Range Names and inter-sheet links. but no links to other files.
My OL calc version is 4.4.0.3 running on Win 7 Professional with a Intel i5-2500k CPU @ 3.30Gz and 8.00GB shared memory & System type 64-bit operating System
Any clues why crazy slowness? Makes saving document a real hurdle but can’t avoid. The above change dramatically improved general responsiveness but has done nothing for the savings problem!
There is probably a setting I’ve overlooked that needs setting!
I use sheet for diabetee control. And changing to Excel not an option!