I recently came across an Apple 27" Cinema HD Display, which is 2560x1600 and connects through DVI. I have a fairly powerful gaming PC, GTX 770 graphics card, i5-6600k, SSD, and 16 GB RAM. I definitely have the hardware capable of driving this monitor.
When I boot up Windows, I can use this Apple monitor just fine. It works at its native 2560x1600 resolution and displays content at 60Hz and full color.
However, when I boot up my Xubuntu 18.04 Linux, any time I have this monitor plugged in, Xorg slows to a crawl and stays this way until I reboot. It's insanely slow, the mouse cursor freezes for seconds at a time, and applications take forever to load. Sometimes a severely distorted image of my first monitor appears on the screen, despite the display set to "extend". If I unplug the Apple monitor and reboot, then my OS works fine, but breaks again when I plug it back in.
I'm able to press Ctrl+Alt+F1 and run
htop to see Xorg flooring it at 100% CPU usage. Beyond observing the problem I have no idea what I could do to fix it.
I'm using the proprietary Nvidia drivers for my GTX 770 from the
graphics-drivers 18.04 PPA.