I must admit that the Steam client is quite slow and bloated. Having used it for many years, I often avoid launching it. Epic has replicated these same issues. Consequently, I end up using GOG instead.
Interestingly, the Epic store is not, or rather it is but it uses Unreal to render it (or at least the Slate UI component of it). On my laptop it uses the discrete GPU to render instead of the integrated one, which has an impact on power use and battery life.