That matches my experience as well...except for the "look up" hanging...I don't have any issues with that. And highlighting is working great - I literally use it every day. I'm running iOS 17.03 (iphone 11 pro...I know...just can't seem to find a reason for a newer one
).
I also tried Marvin's "look up in Wikipedia" in addition to Apple's "Look up" option and both seemed to work fine. Perhaps there is some other option/setting that is causing a conflict??