I have a similar problem on Ubuntu 17.10: cheese takes about 15 seconds to start using an UVC camera (046d:0990) on USB3 but start immediately using an old Philips 740 webcam.  

corrado@corrado-p5-0930:~$ cheese

(cheese:5526): Gtk-WARNING **: Theme parsing error: cheese.css:7:35: The style property GtkScrollbar:min-slider-length is deprecated and shouldn't be used anymore. It will be removed in a future version
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
corrado@corrado-p5-0930:~$ 

corrado@corrado-p5-0930:~$ inxi -Fx
System:    Host: corrado-p5-0930 Kernel: 4.13.0-12-generic x86_64 bits: 64 gcc: 7.2.0
           Desktop: Gnome 3.26.0 (Gtk 3.22.21-0ubuntu1) Distro: Ubuntu Artful Aardvark (development branch)
Machine:   Device: desktop Mobo: ASRock model: H110M-G/M.2 serial: N/A UEFI: American Megatrends v: P1.10 date: 05/11/2017
CPU:       Dual core Intel Core i3-7100 (-HT-MCP-) arch: Skylake rev.9 cache: 3072 KB
           flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 15648
           clock speeds: max: 3900 MHz 1: 3900 MHz 2: 3900 MHz 3: 3900 MHz 4: 3900 MHz
Graphics:  Card: Intel HD Graphics 630 bus-ID: 00:02.0
           Display Server: x11 (X.Org 1.19.3 ) driver: i915 Resolution: 1920x1080@60.00hz
           OpenGL: renderer: Mesa DRI Intel HD Graphics 630 (Kaby Lake GT2)
           version: 4.5 Mesa 17.2.2 Direct Render: Yes
Audio:     Card-1 Intel Sunrise Point-H HD Audio driver: snd_hda_intel bus-ID: 00:1f.3
           Card-2 Logitech QuickCam Pro 9000 driver: USB Audio usb-ID: 001-006
           Sound: Advanced Linux Sound Architecture v: k4.13.0-12-generic
Network:   Card: Intel Ethernet Connection (2) I219-V driver: e1000e v: 3.2.6-k bus-ID: 00:1f.6
           IF: enp0s31f6 state: up speed: 100 Mbps duplex: full mac: 70:85:c2:44:7b:86
Drives:    HDD Total Size: 1000.2GB (6.9% used)
           ID-1: /dev/sda model: TOSHIBA_DT01ACA1 size: 1000.2GB
Partition: ID-1: / size: 32G used: 4.7G (16%) fs: ext4 dev: /dev/sda5
           ID-2: swap-1 size: 8.59GB used: 0.00GB (0%) fs: swap dev: /dev/sda2
RAID:      No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors:   System Temperatures: cpu: 37.0C mobo: N/A
           Fan Speeds (in rpm): cpu: N/A
Info:      Processes: 238 Uptime: 2:58 Memory: 1428.4/7684.1MB Init: systemd runlevel: 5 Gcc sys: N/A
           Client: Shell (bash 4.4.121) inxi: 2.3.37 
corrado@corrado-p5-0930:~$ 


in the log i see:

15:36:02 systemd: Started Hostname Service.
15:36:02 dbus-daemon: [system] Successfully activated service 'org.freedesktop.hostname1'
15:36:02 systemd: Starting Hostname Service...
15:36:02 dbus-daemon: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service'
15:36:02 dbus-daemon: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service'
15:35:22 dbus-daemon: Successfully activated service 'org.gnome.Logs'
15:35:22 dbus-daemon: Activating service name='org.gnome.Logs'
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1280x1024"x0.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1280x1024"x0.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1280x800"x0.0   71.00  1280 1328 1360 1440  800 803 809 823 +hsync -vsync (49.3 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1680x1050"x0.0  119.00  1680 1728 1760 1840  1050 1053 1059 1080 +hsync -vsync (64.7 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1440x900"x0.0   88.75  1440 1488 1520 1600  900 903 909 926 +hsync -vsync (55.5 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1600x900"x60.0  119.00  1600 1696 1864 2128  900 901 904 932 -hsync +vsync (55.9 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1280x720"x60.0   74.48  1280 1336 1472 1664  720 721 724 746 -hsync +vsync (44.8 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1024x768"x0.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "640x480"x0.0   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "800x600"x0.0   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz e)
15:35:05 gdm-x-session: (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
15:35:05 gdm-x-session: (II) modeset(0): Printing DDC gathered Modelines:
15:35:05 gdm-x-session: (II) modeset(0): Using vrefresh ranges from config file
15:35:05 gdm-x-session: (II) modeset(0): Using hsync ranges from config file
15:35:05 gdm-x-session: (II) modeset(0): EDID vendor "HPN", prod id 13179
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1280x1024"x0.0  108.00  1280 1328 1440 1688  1024 1025 1028 1066 +hsync +vsync (64.0 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1280x800"x0.0   71.00  1280 1328 1360 1440  800 803 809 823 +hsync -vsync (49.3 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1680x1050"x0.0  119.00  1680 1728 1760 1840  1050 1053 1059 1080 +hsync -vsync (64.7 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1440x900"x0.0   88.75  1440 1488 1520 1600  900 903 909 926 +hsync -vsync (55.5 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1600x900"x60.0  119.00  1600 1696 1864 2128  900 901 904 932 -hsync +vsync (55.9 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1280x720"x60.0   74.48  1280 1336 1472 1664  720 721 724 746 -hsync +vsync (44.8 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1920x1080"x60.0  172.80  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1024x768"x0.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "640x480"x0.0   25.18  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "800x600"x0.0   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz e)
15:35:00 gdm-x-session: (II) modeset(0): Modeline "1920x1080"x0.0  148.50  1920 2008 2052 2200  1080 1084 1089 1125 +hsync +vsync (67.5 kHz eP)
15:35:00 gdm-x-session: (II) modeset(0): Printing DDC gathered Modelines:
15:35:00 gdm-x-session: (II) modeset(0): Using vrefresh ranges from config file
15:35:00 gdm-x-session: (II) modeset(0): Using hsync ranges from config file
15:35:00 gdm-x-session: (II) modeset(0): EDID vendor "HPN", prod id 13179
15:34:45 systemd: Started GNOME Terminal Server.
15:34:45 dbus-daemon: Successfully activated service 'org.gnome.Terminal'
15:34:45 systemd: Starting GNOME Terminal Server...