Random Freezes when performing any action.

I have had this problem before, I even thought i’d posted about it, but apparently not. If I have scenes above a certain size and complexity in blender. It starts to freeze up when making changes. This problem has happened in numerous scenes so is not related to the content within the blend file.

In a large scene. When making a change in the scene, from ticking a checkbox in the world options, to altering a camera view distance, to moving a piece of geometry. Not EVERY time, but about every 3rd or 4th change, blender will freeze. The freezes are only consistent in that above a certain file size, they get proportionally bigger with the added level of complexity in the scene. However in my most recent scene these delays are about 20-30 seconds. I have checked my system, blender is only using 4gb of ram from my 16. Its not running out of memory, and its not crashing. Just freezing on random changes, irrespective of whatever action has just occurred.

I have googled and not found a solution or even a hint of this problem happening with other people. There is no problem using other programs, the problem is specifically with blender and large scenes. I have also optimized my scenes, losing between 40-60% of the initial filesize. Which means it’s probably a bit of a fringe problem. My system is pretty decent, and here are the specs:

AMD Phenom II x6 1055T @ 2.6Ghz per core
16GB Memory
NVidia GTX460 GFX card.
Windows 7 64bit
110GB Free hard disk space.

Any and all help is appreciated!