I am also using pi zero and my boot time is in the 15-20 sec range per dmesg...
I have /mnt/mmcblk0p2/tce/copy2fs.flg so that all extensions are loaded into RAM at boot, and then the SD card partition gets unmounted. Seems safer, but that adds to boot up time. onboot.lst contains:
w1-4.9.22-piCore.tcz
mc.tcz
openssh.tcz
firmware-rpi3-wireless.tcz
wifi.tcz
requests.tcz
pyinfluxdb.tcz
rpi-vc.tcz
which results in dmesg ending:
[ 3.722558] gpiomem-bcm2835 20200000.gpiomem: Initialised: Registers at 0x20200000
[ 4.266170] zram: Added device: zram0
[ 4.319183] zram0: detected capacity change from 0 to 106156032
[ 4.346338] Adding 103664k swap on /dev/zram0. Priority:-1 extents:1 across:103664k SSFS
[ 4.655151] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 7.477899] EXT4-fs (mmcblk0p2): recovery complete
[ 7.480982] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 7.707177] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 21.777788] Driver for 1-wire Dallas network protocol.
[ 21.779851] w1-gpio onewire@0: gpio pin 4, external pullup pin -1, parasitic power 0
[ 21.779889] w1_add_master_device: set_pullup requires write_byte or touch_bit, disabling
[ 22.853016] usbcore: registered new interface driver brcmfmac
[ 22.951449] brcmfmac: Firmware version = wl0: May 27 2016 00:13:38 version 7.45.41.26 (r640327) FWID 01-df77e4a7
[ 24.074855] i2c /dev entries driver
[ 24.127136] uart-pl011 20201000.serial: no DMA platform data
[ 25.644115] brcmfmac: power management disabled
[ 356.012500] random: crng init done
I've no idea why that last line comes after such a long gap. Also, not sure at what point the wi-fi connection is up, as that's when my application (a heating system monitor, and later, control too).
I have another project using a Pi version 1 model B, with onboot.lst:
mc.tcz
openssh.tcz
samba4.tcz
bash.tcz
curl.tcz
lftp.tcz
gawk.tcz
rpi-vc.tcz
mutagen.tcz
sox.tcz
and dmesg ending:
[ 4.262045] sda: sda1
[ 4.266119] sd 0:0:0:0: [sda] Attached SCSI removable disk
[ 4.428706] gpiomem-bcm2835 20200000.gpiomem: Initialised: Registers at 0x20200000
[ 4.733112] zram: Added device: zram0
[ 4.906648] zram0: detected capacity change from 0 to 52543488
[ 4.936480] Adding 51308k swap on /dev/zram0. Priority:-1 extents:1 across:51308k SSFS
[ 5.420546] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 7.213699] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 7.377363] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 34.661679] i2c /dev entries driver
[ 35.100922] NET: Registered protocol family 10
[ 35.361342] random: crng init done
[ 35.399562] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[ 35.495912] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[ 36.804036] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xD1E1
which receives recordings from a networked audio recorder installed in the sound desk at the church I attend, processes them and uploads the results to an FTP site for linking into the church website. This is the one I needed Samba for, as the network recorder only knows how to upload to a Windows share.