Jade,
Good question. The best way to optimize the site and the slideshow is to make the images as small as possible. The script that loads the slideshow is at the bottom of the page, so it won’t load until everything above it has finished rendering. The more data that is in the page above it, the longer it will take to initialize.
While it will still work with images in the 250 to 300 kb range, for the dimensions of the slider, you can have images that appear of good quality, but are less than 50 kb. In the demo, most of the slider images are around 25 kb.
I would suggest making the file sizes smaller. In addition to that, make sure you do need every plugin is running. A good many of the ones running at the moment load quite a bit of stylesheets and javascript which will also slow down the site.
The last thing i would do is set up a caching plugin like WP Super Cache. That one has the ability to compress your content so it’s smaller as it’s transmitted to your visitors which will make it faster too. I would wait to deploy the plugin until you’re finished developing though.
If I can help at all, just let me know.
Thanks and have a great week,
Bill