A SCEE spokesperson released a statement on the European PlayStation forums yesterday about slow loading times for icons on the newly revamped PS Store:
As you will have noticed, the PS Store re-launched successfully today, and we'd like to thank you for your positive feedback.
We are aware that many of you have experienced delays whilst the PS Store's thumbnail icons are being downloaded. This is a temporary consequence of a new system implementation and high global traffic levels, and will be resolved within the next few days.
Thank you for your patience and continued support!
Hopefully things will settle down after you all stop, you know, using your PS3s. Oh.