I was just in Activity Monitor to check on another problem child when I noticed there was a new King of the Hill... iconservicesagent was clocking in 13.59 GB of Memory (12.12 GB of it compressed) 2 threads.

The next one in line is our beloved kernel_task, at 1.71 GB.

So any idea what gives? I use a lot of custom file and folder icons here, is that related? Still seems very excessive!

My uptime is 26 days... ok maybe TTR, but still... this is the only obvious issue right now. It's not really being sluggish or anything. 10.12.6.

On my system running MacOS 0.13.3 beta there is one iconserviceagent task using 14.7 MB with 4 threads belonging to the user and a second iconserviceagent task using 2.8 MB? with 2 threads belonging to root. For comparison kernel-task comes in at 1.63 GB.

On another machine running MacOS 10.13.2 there is one iconservicesagent task at 7.4 MB with 4 threads using 7.4 MB belonging to the user. There is no iconservicesagent task of root as the machine is running headless.

FWIW a DuckDuckGo search for iconservicesagent turned up a lot of hits complaining of excessive memory use running back several MacOS generations but a cursory look found no apparent universal fix other than forcing the task to quit.

For comparison, some details from me:
macOS 10.12.6 - Uptime: 2 days, 7:50
iconservicesagent 0.0 % cpu 2.26 cpu time 51.2 MB mem 0 bytes compr.mem 2 threads user
iconservicesagent 0.0 % cpu 0.10 cpu time 15.4 MB mem 1.3 MB compr.mem 2 threads root
kernel_task 0.9 % cpu 27:39.58 cpu time 1.24 GB mem 0 bytes compr.mem 140 threads root

My iconservicesagent is nowhere near your size. My Photoshop puts custom icons on most saved files, but other than that I don’t play as much with custom icons as I used to. But I remember the small 32x32 icons of Mac OS 7.x, and the huge icons sets of 512x512 that we have now. Caching loads of icons on the off-chance that they need to be shown again, will add up with time (if it works like: cached as needed from the first instance they were shown, i.e. Desktop and all folders that have been openend to reveal their content)

ok sounds like a bug then. A few months ago I noticed my mac was redline on memory and quickly realized my IRC client was consuming 64gb of ram! RELAUNCH!