system-config-printer unusably slow

When I try to load system-config-printer, it takes tens of seconds to load. Any interactions take many more seconds, to the point that this utility is unusable.

When I strace initial loading, here is what I get:

socket(PF_INET6, SOCK_STREAM, IPPROTO_IP) = 16
setsockopt(16, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
setsockopt(16, SOL_SOCKET, SO_REUSEPORT, [1], 4) = 0
setsockopt(16, SOL_TCP, TCP_NODELAY, [1], 4) = 0
fcntl(16, F_SETFD, FD_CLOEXEC) = 0
fcntl(16, F_GETFL) = 0x2 (flags O_RDWR)
fcntl(16, F_SETFL, O_RDWR|O_NONBLOCK) = 0
connect(16, {sa_family=AF_INET6, sin6_port=htons(631), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress)
fcntl(16, F_SETFL, O_RDWR) = 0
poll([{fd=16, events=POLLIN|POLLOUT}], 1, 250) = 0 (Timeout)
poll([{fd=16, events=POLLIN|POLLOUT}], 1, 250) = 0 (Timeout)
poll([{fd=16, events=POLLIN|POLLOUT}], 1, 250) = 0 (Timeout)
poll([{fd=16, events=POLLIN|POLLOUT}], 1, 250) = 0 (Timeout)
...

IPv6 is disabled on my system:

ezyang@sabre:~$ cat /proc/sys/net/ipv6/conf/all/disable_ipv6
1

This pattern seems to repeat whenever the interface hangs.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: system-config-printer-gnome 1.5.6+20150318-0ubuntu2.1
ProcVersionSignature: Ubuntu 3.19.0-21.21-generic 3.19.8
Uname: Linux 3.19.0-21-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
Date: Fri Jul 17 15:05:17 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-11-21 (603 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MachineType: LENOVO 7762K3U
PackageArchitecture: all
Papersize: letter
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
PpdFiles:
 Error: command ['fgrep', '-H', '*NickName', '/etc/cups/ppd/mitprint-color.ppd', '/etc/cups/ppd/mitprint.ppd'] failed with exit code 2: grep: /etc/cups/ppd/mitprint-color.ppd: Permission denied
 grep: /etc/cups/ppd/mitprint.ppd: Permission denied
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-21-generic root=/dev/mapper/hostname-root ro quiet splash vt.handoff=7
SourcePackage: system-config-printer
UpgradeStatus: Upgraded to vivid on 2015-05-29 (49 days ago)
dmi.bios.date: 03/22/2011
dmi.bios.vendor: LENOVO
dmi.bios.version: 7SET39WW (1.25 )
dmi.board.name: 7762K3U
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr7SET39WW(1.25):bd03/22/2011:svnLENOVO:pn7762K3U:pvrThinkPadX61Tablet:rvnLENOVO:rn7762K3U:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 7762K3U
dmi.product.version: ThinkPad X61 Tablet
dmi.sys.vendor: LENOVO