Terry, if your website contains many or large images this can heavily impact on the speed of your website. Have you looked in step 5? I would start with Optimise website but then go to Export Project. Here there is an option to automatically Reduce the Resolution of Larger Images (I never include backups or previews).

Once you have generated the iwzip file, open WX5 and select import. This will NOT overwrite your existing project. Upload this new project and check the results.

If speed is still not acceptable, please post a link to your site here so we can all have a look.