Update (2019): The issue still persits even in macOS Mojave, tried everything I could find, nothing seems to solve the issue as of yet!
Problem:
com.apple.hiservices-xpcservice hangs repeatedly ever since I upgraded to macOS Mojave 10.14.1. Now,everytime the process hangs it is indicated by red colored fonts in the Activity Monitor. Due to the frequent hangs my system slows down and it's barely usable due to extremely slow performance.
What I have done so far:
I have already Googled it (The Process) and also contacted Apple regarding the usage of this process and the reason behind it's frequent hick-ups. Alas! they couldn't help much.
So, I terminated the process.
Temporary Solution:
As soon as I terminated the process (com.apple.hiservices-xpcservice) my mac started running fast once again.
But, whenever I restart the system or leave the mac idle for a few minutes and then if I start using it once again! out of no where, the process (com.apple.hiservices-xpcservice), shows up once again in the activity monitor resulting in slow performance issues along with hangs and freezes across macOS.
System Info:
Model
iMac (27-inch, Mid 2014)
Processor
3.5GHz quad-core Intel Core i5 processor (Turbo Boost up to 3.9GHz)
Configurable to 4.0GHz quad-core Intel Core i7 (Turbo Boost up to 4.4GHz).
Memory
8GB (two 4GB) of 1600MHz DDR3 memory; four SO-DIMM slots, user accessible
Configurable to 16GB or 32GB.
Storage
1TB Fusion Drive
Screenshot Of The Process com.apple.hiservices-xpcservice
Best Answer
Had the problem too.
Tried to disable SIP, then remove execution rights on com.apple.hiservices-xpcservice, reboot after re-enabling SIP.
Result : Safari keeps crashing, each time it opens so it seems to be linked to apple apps.
Giving back execution rights on the service repaired Safari ..
Except killing it when it becomes unresponsive, I don't see any other solution