This is from an excellent website called WhichTestWon.com that performs A/B testing of verious website functions and features. The version on the left used six static images on the home page. The version on the right used a slideshow. The version on the left had a 187% higher click-through rate and increased sales by 75%.
Slideshows are OK if they are used as an 'accent' feature, but if you try to use them to present facets of your sales or marketing message you are probably doing yourself more harm than good. Website viewers are not going to wait around to view the whole thing in hopes that one of the slides resonates with them.
Designers love sliders. but you should engineer your website for revenue.