The DiskUsage app shows 14,8MB data used for "Internet" and 11,5MB used for contacts.

Is there a way to reduce memory usage? 

I know I can delete Internet data using the general app settings but I fear this will also delete all saved passwords and I'd like to avoid that.

As for the contacts: In the global account settings (sync) I use only my two Google accounts and weather. I had Facebook sync activated while back, though, and it import a number of contact photos, which are still visible.

Any chance to reduce memory usage without removing too much useful data?