The thumbnails preference determines whether or not you see small images beside each product when browsing the catalogue. Switching this off will speed up the time the page takes to load (ideal for those using a dial-up connection).
Products per page
The products per page preference determines how many results are displayed on each page. Lower numbers will speed up the time a page takes to load, but will result in more pages of results.
Number of recent items
We can remember the last few products that you looked at to help you browse and compare items. Use this setting to decide how many recent items to remember.