You don't find many elite level athletes that are vegan's and those that are supplement their training quite heavily.
If you want optimum performance you have to experiment a bit with what feels best AND gives your body what it needs to recover and rebuilt.
Personally, for me, I have tried the vegan/vegetarian way a few times in the past and it didn't work for me BUT know some that it worked great for ( with supplementation though).
Psalms 144:1
Praise be my Lord my Rock,
He trains my hands for war, my fingers for battle !