Emacs regularly hangs multiple seconds in e.g. find-file

[Alexander Asteroth]

Dear all,

I'm using GNU Emacs 26.0.50.1 (x86_64-pc-linux-gnu, GTK+ Version 3.18.9)
on top of Ubuntu Linux 4.4.0-92-generic #115-Ubuntu SMP Thu Aug 10
09:04:33 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux, as Editor,
Window-Manager (exwm), ...

Unfortunately after start it regularly hangs for 10 or more seconds when
doing find-file or when starting a process (with autocompletion). The
frequency of these hangs reduces as emacs uptime increases.

I tried an strace and figured out, it probably hangs in a read:

...
     0.000733 recvmsg(6, 0x7ffdfdb31430, 0) = -1 EAGAIN (Resource temporarily 
unavailable)
     0.000273 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000230 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000435 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000202 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000288 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000177 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000390 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000159 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000199 recvmsg(6, 0x7ffdfdb31430, 0) = -1 EAGAIN (Resource temporarily 
unavailable)
     0.000158 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000148 recvmsg(6, 0x7ffdfdb31650, 0) = -1 EAGAIN (Resource temporarily 
unavailable)
     0.000086 poll([{fd=6, events=POLLIN}, {fd=7, events=POLLIN}, {fd=10, 
events=POLLIN}], 3, 0) = 0 (Timeout)
     0.000117 pselect6(15, [4 6 7 10 12 13 14], [], NULL, {1, 911848155}, 
{NULL, 8}) = 1 (in [4], left {1, 4014190})
     0.908089 read(4, "\1\0\0\0\0\0\0\0", 8) = 8
     0.000229 pselect6(15, [4 6 7 10 12 13 14], [], NULL, {1, 3617217}, {NULL, 
8}

I tried three times and always the last call seems to be this
read(4,...).

Any suggestion what could be the cause?

Thanks for any hint!

Cheers,

        Alex