Genuinely curious what your life is like such that an email app that takes longer than 1/10th of a second is just beyond the pale? Are you really that time poor?
It's really nice to have fast response clients. .1 or .3 seconds doesn't matter in the sense of saving 1000 seconds a day probably, but immediate response from tools is useful.
gmail is significantly slower: it's not like 1/10th of a second vs 3/10th of a second.