How to get previous shutdown cause

There is some software running or hardware plugged into your mac that is deliberately delaying the shutdown process for some reason.

It's hard to know what it is, except to start randomly uninstalling and/or unplugging stuff. In general, a clean install of OS X with no third party hardware plugged in will shut down in a split second, but once you install a bunch of stuff it starts to take longer and longer.

You could narrow it down by testing how long it takes to shut down while at the login screen, or by logging in as a different user (create a new blank user account just to test it) and shut down from there. If it's faster, then it is probably something in your login items that slows things down.

Or, it could be a kernel extension, system daemon (apache/mysql causes slow shut downs on my mac), mouse driver, printer driver, etc that is causing the slow down. In those cases it won't matter if you are logged in or logged out when you shut down.

In general though, you're not looking for a single problem. There are probably 20 or 30 things slowing down your shutdown process. From the look of the log, you sent, it's sending a shutdown message to a bunch of stuff in a single second, then taking about 40 seconds for all of them to actually close. It does not do them one at a time, it does all of them simultaneously.

You might want to start by looking into that log message "No plugin provides credentials for account e.....n@gmail.com." - that suggests something on your mac is logging into a remote server during the shutdown process, and probably delaying the shutdown until it gets a response.

As for your main question about bootcamp... No. It's highly improbable that Bootcamp causes any performance impact at all, unless you start running very low on disk space (some disks, especially SSD drives, tend to run slower if they are over 90% full).

As it turned out, my battery had reached and surpassed the end of its life. It was rated good for 1000 full charge cycles; it had gone through nearly 1200 (in roughly a five-year time span.)

I got the battery replaced and all was well.