Load an array in editor while keeping unity running

Hello :)

I need some help please. I need to load an Serialized array which is relatively large (aprox 50000). This obviously takes a bit of time when put into a for loop and unity is practically useless at that time without even having the possibility to show progress done.

I would like to run this process in the background. The only problem is that Editor scripts do not have a type of Update(), instead it updates when something is changed.

I already explored several options like:

http://answers.unity3d.com/questions/39313/how-do-i-get-a-callback-every-frame-in-edit-mode.html

and it works great for a single array. But when I wont to load different arrays for different objects its no good since its a static constructor.

Any of you guys have an idea on how to deal with this issue?

Thanks :)