It's very true. The click isn't the problem, the "waiting for transition between pages" is the problem.

Type username/password = ~1s each

Single keypress = ~0.1s each

Page load = ~2s

Before: username + tab + password + enter = 1 + 0.1 + 1 + 0.1 + 2 = ~2.2s

After: username + enter + page load + password + enter = 1 + 0.1 + 2 + 1 + 0.1 + 2 = ~4.2s

Roughly doubling the amount of time it takes to enter your information is significant and annoying.