Opera 45.0.2552.812, latest Arch Linux.
Right from start Opera burns CPU with poll() loop as shown by strace: 
It is always 2 file descriptors, in this case, 110 and 117.
Looking at it closer, strace shows backtraces for each EAGAIN'ed recvmsg: 
Looks like it has something to do with X server interaction.
Checking those descriptors here: 
Closing those descriptors via gdb results in Opera SIGSEGV.
Always reproducible, even with clean profile and no extensions.
Is there any option how to save my CPU cycles?