Do you read with a pen?

I don't feel like I've read a book unless I underline and mark it.

I don't know why but it feels like a waste to not mark stuff for future reference.

But it. Makes. Me. So. Soo. Sooo. Slow

I tried to read the Great Gatsby without marking anything and finished it in like 3 hours Now that I'm re-reading it a while later while trying to mark beautiful lines and descriptions, I can't even seen to finish it. It's giving me such a headache lol.

This habit stops me from picking up other books that I really really want to read just because of the inertia.

What do you guys do? Leave the book blank? What if you find a line that's extremely beautiful? Don't you fear that you're going to forget it?