The Intel drivers aren't that crappy, it's just low-end 3D chips. You can't expect full performance on these.
That said, it's still a sign of problems in CS (Crystal Space) if 0.4 ran smoothly and 0.5 doesn't.
On the other hand, it's hard to test for every chip and every driver that's out there.
On the third hand, completeness of testing with graphics drivers is one of the differences between high-quality and not-so-high-quality graphics libraries.
On the fourth hand, switching to another graphics library is probably not an option.
Back to the problem at hand - have you tried downgrading the graphics settings in the launcher?
Some settings can have a dramatic impact, particularly on low-end cards.