IMO, it'll probably still be slow at a lot of things. The gen-6 i5-U laptops we at my job use have SSDs and 8GB ram (granted, also running windows because required for some software) and they're still really slow compared to things like my personal desktop and laptop. Boot times are fine at least, but web browsing isn't as quick and responsive as I'm used to (<2 seconds per page). They probably take more like 10 pages to load pretty basic pages (no videos).
Still, probably a ton faster with an SSD than without one.