Should I implement multiple changes at once?

I'm currently managing an e-commerce store and considering several potential improvements to my conversion strategy. These include adding new discount mechanisms, redesigning product pages, implementing exit-intent popups, and adjusting pricing. I'm uncertain whether I should implement all these changes simultaneously or take a more measured, step-by-step approach. My primary concerns are maintaining site performance, accurately tracking the impact of each modification, and avoiding overwhelming my customers with too many changes at once. What's the most strategic way to approach multiple optimization efforts?