High Sierra slow booting

Having the same issue on my MacBook Pro 13" Mid 2014. My SSD usually takes 8-10 seconds to boot, but now its take almost a minute. Hopefully as the betas progress, Apple will fix that issue because it is really annoying.

After installing beta5 my MBP mid 2011 was booting in 23 seconds. Now after installing beta6 the slow boot is here again. Imac 27 mid 2010 needs 65 seconds no change anywhere.

my late '16 15" MBP takes 15+ seconds for the screen to come on ... after initiating a start up.

if I walk away from my machine for some short time (I haven't timed it yet) -- like 5 minutes (or 10?) -- the screen is off and when I interact with the machine -- the screen starts to brighten up and the locks -- and after 45 seconds -- crashes/reboots.

this has happened with each beta so far and continues with 12.13b6

Using last beta 17A344b, boot time : 52 seconds on iMac 5K 2017 2TB fusion drive, APFS

30 seconds after pressing poweron button showing black screen (Thank you apple to remove boot sound e grey logo screen.. >:| ) and 22 seconds to see the login window.

I can't use the sleep mode, after a while a question mark appears on the screen and I have to poweroff using physical button.

Also after installing the GM there isn´t any change of the slow startup. Now I installed it on a third Computer (mac mini mid 2011 with the same effect. Thank yxou APPLE for installing a "booting brake" on all of my Macs. My Dell venue (Win 10 Creators update) is booting in 14 seconds for comparison.

The first (and so far only) GM takes about two minutes to boot from a thunderbolt SSD with APFS.
I thought the boot process was hanging.

I have the same issue..

MacBook Pro Mid 2015

I have an iMac late 2013 with ssd and it works fine with High Sierra Release, but my MBP 13inch late 2011 with 8GB and SSD takes more than 50s to boot and the apps takes in some cases more than 15s to load.

I used verbose in boot and it takes time in IOGraphics Flags

Macbook Pro 2015 13" Here, also experiencing slow boot up (Final release). Didnt time it but it's a notable slow down from Sierra.

I had the same experience with my MacBook Pro mid 2012 and my Samsung 840 evo 1tb.

After two days of trying, I found out that disabling the trim command by "sudo trimforce disable" fixes my bug permanently and reproducibly.

Thank you Mr.X. disabeling an re-enabling trim fixed my issue

I also found this by trying your tip. Disabling trimforce results in normal restart times. But reenabling makes the system slow again in booting.

Are you sure, you got fast boot-timing after re-enabling trim ?

In my Case reenabling trim, it slowed down my Mac again too. Mr. X

Have you installed DISK SENSAI?