> I think the slowdown was being caused by a
> repeated call to package-initialize, which I now avoid by disabling
> package-enable-at-startup in early-init-file.

Might it be a good idea to have `package-initialize' signal a warning if
it's
called multiple times? I hadn't considered this side effect of the change,
but at least it's easier to get users to remove a duplicate call than to add
a missing one.

Are there ever circumstances where calling `package-initialize' more than
once makes sense? Perhaps we can allow for those by introducing a
variable `package-warn-on-reinitialization' or somesuch, which would be
set to non-nil in `package-initialize', and then next time around produce a
warning, but then could be set back to nil to suppress the warning.