There are two issues here.
1. Projectile uses file-remote-p to check for remote (tramp) paths in
its known project list, when it automatically cleans it up on
projectile-mode's activation. This causes tramp.el to be loaded,
which is expensive.
2. file-remote-p relies on an entry in file-name-handler-alist
(autoloaded by tramp.el) to detect remote paths, which causes tramp
to be loaded. However, Doom sets file-name-handler-alist to nil at
startup for a noteable boost in startup performance.
Normally, this is not an issue, as I defer projectile-mode until well
after file-name-handler-alist is restored, but it is trivial for a
user to inadvertantly load it too early (often as part of another
package that depends on it, or by blindly following projectile's
install instructions and calling projectile-mode themselves).
In order to address both of these, I defer projectile's cleanup process
altogether. Another approach I considered was to ensure projectile-mode
wasn't activated until the right time, regardless of when projectile is
loaded, but this may trouble savvier Emacs users who need projectile's
API early during startup, so it needs more consideration.
Fix: #6552
Ref: bbatsov/projectile#1649
42ac62df74