My understanding (I'm not sure I'm getting this all right) is that if one uses Trim on an encrypted SSD, it defeats some of the security benefits, because the drive will write zeros to empty space (as files are deleted).

See: http://www.askubuntu.com/questions/115823/trim-on-an-encrypted-ssd And: http://asalor.blogspot.com/2011/08/trim-dm-crypt-problems.html

My question is: From the perspective of the performance of the SSD and the functioning of Trim, would it therefore be better to simply zero out the SSD, before setting up an encrypted system, rather than writing random data to the drive, with urandom, as one usually does?

Would this basically leave one with the same level of security anyway? And more importantly, would it better enable the Trim functionality to work as intended, with the encrypted SSD?