Going Bananas

Compared to bananas, they are slow.

But among palms, there are rocket and some snails.
With palm hybrids, you would get synergistic qualities
of both parents in terms of cold resistance and speed of growth.
Palmtalk.org has excellent threads/topic on hybridization(palms)
especially Butia x Parajubea cocoides.
Patrick Schaefer from Northern California
is well known in the site for producing those hybrids.