The mechanical connector layout forces sub-optimal signalling paths. You're forced to make everything slower to make things consistent. That being said, a mor

The mechanical connector layout forces sub-optimal signalling paths. You're forced to make everything slower to make things consistent. That being said, a more optimized connector, board layout and form factor could make large-capacity, lower-latency modules possible. Not sure for example if there is anything out there besides the Dell proposed CAMM form factor, and I don't remember that one being specifically promoted as "faster", mostly "smaller".