Slow response when 'reawakening' laptop

[shivvy]

My laptop switches to showing a slideshow of my photos after x minutes of it being idle.

It has been set this way for many months and I usually just have to move the mouse to 'reawaken' the screen. However over the last couple of days it has been slow to respond.
I have restarted the laptop which hasn't helped. Is there something else I could do?

Thanks.

[LeMarchand]

Do you have a lot of folders on your desktop? Could possibly be having to index the contents. If so, move them off and leave shortcuts to them.

[shivvy]

I have the same amount on my desktop as I had before LeMarchand.

[shivvy]

This is really frustrating me.
Can anyone help?