Thumbnails are really slow since a few updates

Hi,

I set up my XBMC in August on a Triple Core APU(ATI) with 4gig RAM on a SS in August. Everything was running just fine until some weeks ago when I did an auto update. Now, the thumbnails load really slow, it is almost as if they are getting downloaded.
I tried deleting the MyTexture DB and the Thumbnails-Folder. I also used the Texture Cache Maintenance Utility.
Nothing helped so far. No matter what I do if I scroll fast back and forth I am getting a blank case where the images should be. The Info and everthing runs fast though.

Can someone help me on this, please?

Thanks,
Kiesel
(13.0-ALPHA3 Git:41061a8), Platform: Linux (Ubuntu 12.04.2 LTS, 3.2.0-29-generic x86_64). Built on Apr 5 2013