It does? Huh, there are only 204 images.

I tested it like I say from Lc 6-8, nothing slowed down here, even in 8.1.6 (Linux). Curious, do you still have any earlier Lc's on the machine? Does it slow down there?
My machine is hardly a speedster, being an athlon 2 x3 3.2GHz. from 2010.
This does bring up another question I (& the rest of us) should probably know, is there some upper limit we should avoid in the number of icons in a particular libary? 100? 1000? Most of the libraries I have are under 500, but I certainly could break them down farther if that would cause issues for someone down the road.
*Edit - On this machine, I have an old Mac set with some 850 in it, and that also comes up fine (here), so I'm not sure.
*Edit 2 - I had just been finishing up some others I had laying around, I'll stick those up and, if changes are required, I'll make those and re-insert later.
One set is the classic delphi bmp format (mostly the same as above, but *does* have some different icons in it). I may just wind up converting them to png and combining the sets. The other is the classic windows icons, which probably run from win 3.x to 98. The last is my collection of B&W mac icons, although over the years I have probably gotten a few that were not, strictly speaking, mac icons but still fit that theme.
I had to upload that last set, as it is too large to put here at 852 images
Old Mac Icons <- let me know if any issues with downloading.
If someone hits an issue like Richard did, please let me know, because I am completely unable to reproduce it.
(303 images)
(411 images).