How to find the cause for high CPU usage of gnome-shell?

I'm on a Linux Fedora 23 and I recently noticed that my gnome-shell process constantly uses 100% of one CPU (reported by htop, no visible applications ruing). There are some hints out there which cover some workarounds for bugs in the gnome-shell (deactivating background logo, re-aligning the monitors) but none of them help.

I tried to run

perf top

which reports the most work in the following symbols:

22.55%  [keel]                            [k] acpi_ns_search_one_scope
11.41%  [keel]                            [k] acpi_ex_system_memory_space_h
 5.27%  [keel]                            [k] _raw_spin_lock_irqsave
 5.23%  [keel]                            [k] _raw_write_unlock_irqrestore
 3.52%  [keel]                            [k] acpi_ut_update_object_referen
 ...

Then I tried to closer look into the gnome-shell process with

perf record -g -p PID
perf report -g

but the output seems to be useless:

  Children      Self  Command      Shared Object                 Symbol       
-   29.08%     0.00%  gnome-shell  [unknown]                     [.] 000000000
   - 0                                                                        
      + 55.88% 0                                                              
      + 8.25% 0x85a81                                                         
      + 6.87% 0x2                                                             
      + 5.94% 0x4                                                             
      + 4.60% 0x889fc                                                         
        3.32% 0x656c6261                                                      
      + 2.39% 0x8feab                                                         
        2.23% 0x88467                                                         
      + 1.26% 0x190800002800                                                  
      + 1.24% 0xffad7fa800100008                                              
        1.23% 0xc82ca96051913c58                                              
        1.20% 0x5602c82afa00                                                  
      + 1.18% 0x1                                                             
        1.16% 0x89e84                                                         
        1.10% 0x5602c7c68830                                                  
        1.08% 0x5602c900736e                                                  
      + 1.08% 0x7ffe4bfd1001                                                  
-   21.48%     0.00%  gnome-shell  [keel.kallsyms]             [k] entry_SYS
   - entry_SYSCALL_64_fastpath                                                
      + 43.62% __GI___ioctl                                                   
      + 18.92% 0xf6fdd                                                        
      + 12.90% __GI___libc_open                                               
      + 5.21% 0xfb4d                                                          
      + 3.92% __GI___libc_recvmsg                                             
      + 2.89% _IO_file_read                                                   
      + 2.75% __socket                                                        
      + 2.74% __GI___libc_read                                                
      + 1.41% __GI___mmap64                                                   
      + 1.39% __GI___libc_recvmsg                                             
        1.30% 0x103b73                                                        
      + 0.77% __GI___writev                                                   
        0.74% __statfs                                                        
      + 0.74% _IO_file_open                                                   
        0.71% __GI___munmap                                                   
+    9.37%     0.00%  gnome-shell  libc-2.22.so                  [.] __GI___io
+    9.37%     0.00%  gnome-shell  [keel.kallsyms]             [k] sys_ioctl

Do you have a hint for me what I could do to to inspect what's going on on my system?

I'm on a Skylake i5 6260u with Intel Iris 540 with Fedora ruing keel 4.3.3-300.fc23.x86_64

- - , .