Unity Editor slow but hardly using any resources?

Hi everyone

My specs:
CPU - AMD FX-8350 8-core, overclocked to 4.8Ghz
GPU - AMD HD 7970, slight overclock
RAM - 16GB

The problem I'm currently experiencing is confusing me slightly.
I'm currently working on a rather big open-world style game with a huge map and loads of assets/animations/sound, etc. Having the editor start to lag was completely expected when I got to this point in my game but the part that's confusing me is I have no idea what's actually causing the lag.
At it's laggiest (usually dragging things about in the Scene view) my CPU usage never gets any higher than about 40% (on one core, never seen it above 20% across all cores at once), my GPU never gets above 35% load and my whole system is only using 3 - 4GB of RAM (with 10Gb free). So my question is, what exactly is causing the lag? Can I increase the amount of resources Unity can use? It seems that if I could increase the amount of resources available to Unity I could be working lag-free.

(Note: Running Unity in Open-GL mode speeds things up slightly when testing the game but runs slower in the scene view. Also, when I build and run my game I get a solid 60fps with low resource usage.)

If this cannot be done, then is my system running Unity at the fastest it can possibly run? That doesn't seem right to me at all.

There's probably something I'm not understanding about how Unity works but if anyone has any answers they'd be very much appreciated

Side note: Unity and all the resources are all saved to my SSD so read/write speed shouldn't be causing any issues.

Thanks

 

Unity 4.x is 32 bit which can't use enough resources, but Unity 5 is 64Bit and should fix this problem,

 

Ah I see, thanks for the reply! I take it no official release date has been announced for 5 yet? I know they initially said Summer but these things always take longer than initially expected.

 

No Initial release yet. but the public beta for pre-order customers should be ready in a month or so..

 

Cool, good to know! Thanks.

 

This may not be a memory issue. You say your whole system is using 3-4GB RAM. How much is Unity using? If it's 3GB or more (which I suspect it's not), lack of available RAM could be the issue. If it's not, going 64-bit isn't going to help you. It's likely there's something else going on here, possibly driver related or related to other software running on your system. Try disabling every memory resident program you can and get the latest video drivers.