Computer has trouble with new 4k monitor (~10fps)

[bopper]

I tested the new 32" 4k monitor at home with my laptop and it was fine. My work machine has trouble with it. Dragging windows around and any motion within apps is a bit laggy. I have a 10th gen I7 and integrated graphics. I'm completely guessing here, but I'd say it's running at 15fps. it speeds up a bit when I unplug the 3rd 1080 monitor and a bit more when I unplug the 2nd. When I pick up a window and rapidly drag it around the screen, it drops to 5 fps. When I did that with the task manager window, it stopped updating the graphs till I stopped moving it. The other two screens handle that test fine and show typical "tails" but they don't seem to lag like the 4k. CPU and GPU only get to ~25% and memory is steady at 50% during this test. FPS is 10ish for youtube from 240 to 4k. CPU bobbles from 60-90% on 4k and hovers at 40% for 240. GPU is a steady 80%. What's the deal here?

Some other oddities:
I have a 3-screen J5 dock (JCD543) with VGA, HDMI, and HDMI-or-DP outs (the "or" seems odd and the VGA seems archaic for a new device). the HDMI-or-DP (tried both) could only output 1440, but the lone HDMI is doing 4k. Any comments on this?

 

[beers]

It's a 5 gbit dock, probably not enough bandwidth.

Something based on thunderbolt would likely perform a lot better.

 

[bopper]

It's a 5 gbit dock, probably not enough bandwidth.

Something based on thunderbolt would likely perform a lot better.

Interesting. I thought docks were just glorified splitters. I guess they are but they still need some processing power to convert signals. This makes makes it make sense. looks like for 60Hz and 8 bit color, 1080p needs 3.73 Gbps and 2160p needs 14.93 Gbps. Now I'm confused about how basically all video streaming works.

Edit: Judging by the absence of the graphic by the USB-C port, it looks like I don't have thunderbolt. Wonder if Lenovo's dock connector has higher bandwidth