Tried on both macvim snapshot 53 and the recent 55.
When I open a Rails directory with "mvim .", it starts up NERD_Tree. When I open any file, it takes about 5 secs to load on my macbook pro intel core duo 2 2.5GHz 4GB of RAM.
I'm mostly using https://github.com/akitaonrails/vimfiles as my vimfile/plugins.
How can I find what's causing the long load time?