Newer versions of Dolphin take advantage of newer features, and if your shitty onboard GPU has drivers missing newer features or implementing them in a broken way, then yeah, Dolphin will be buggier and slower.
3.0 was made in an era where it wouldn't be relying on anything cutting edge or new, but it also will have some graphical bugs like the map depth not working, timestones not rendering correctly, etc.
But yeah, using old builds on extremely outdated/bad hardware is definitely an option, as the optimizations of newer builds often take advantage of newer CPU instructions/features, GPU features, and other things your computer doesn't support. At that point, even though the older build is less optimized, the fact it emulates less makes it faster.
3.0 was made in an era where it wouldn't be relying on anything cutting edge or new, but it also will have some graphical bugs like the map depth not working, timestones not rendering correctly, etc.
But yeah, using old builds on extremely outdated/bad hardware is definitely an option, as the optimizations of newer builds often take advantage of newer CPU instructions/features, GPU features, and other things your computer doesn't support. At that point, even though the older build is less optimized, the fact it emulates less makes it faster.