why is View Using CPU so slow?

[auxiliaryjoel]

Yet another bug I have found with Illustrator is that if I drag my guides, they disappear until I stop moving them, which is extremely unhelpful.

If I change to "View Using CPU" then I can see my guides when I drag them, but the whole app becomes extremely slow.

How do I keep Illustrator running efficiently and also retain the ability to see my guides when I move them?

[Mylenium]

That's mutually exclusive - not in absolute technical terms, but simply how Adobe go about these matters. Instead of fixing AI from the ground up, they view GPU acceleration as a quick fix instead of tackling the actual underlying issues. At best you can hope that updating your system's graphics driver may improve matters, but otherwise it just is what it is. AI has always been slow as molasses in CPU-only modes. There's simply too much old/ bad code under the hood.

Mylenium