WordPress 3.5 'Add Media' button breaking website

Ever since installing WordPress 3.5 and trying to use the new ‘Add Media’ button to add images to my gallery and blog there seems to be an overload and then my whole website crashes. The images I’m uploading which have always been OK before now are around 122kb to 400kb. I’ve contacted the theme provider to see if this is an issue there end and waiting to hear back.

My hosting provider said the following –
‘It looks like the site access was limited because of high resource usage.

Please check this graph to see the CPU usage of your account. http://screens.kgix.net/vc/img_53120431162012.jpg . But it looks like the access was from your IP itself and hence I am lifting the block.’

Any help would be great as I currently can’t update my site without the whole thing crashing.