How to get 4K60FPS/UPS for low end host GPU?

I’m trying to get 4K 60FPS working on my setup.

When I use EGL for render, FPS is closing to UPS and sometimes go higher than UPS.
But It can’t reach 60FPS and 60UPS, only get about 40. looking-glass-client consumes more CPU than GPU.

For OpenGL, FPS is lower than EGL (about 30), but UPS could reach and steady at 60.
looking-glass-client consumes less CPU than EGL.

My host’s GPU is RX550, not good but it can at least play 4K 60 FPS at host.
I think the problem may related to my host GPU, is that the only way to get 4K 60FPS is changing the host GPU?

I’ve test that 2K and scale LG window to 4K resolution, it’s OK with egl but a slight fps drop in opengl. So my host could draw 4k content at 60fps at least. Is there any way to get EGL render 60UPS?

Setup: 5900x, 2x16G 3200Mhz memory, RX550 (Host)/GTX970 (Guest), Looking glass is B5-r403.

Forgive my silly question. Is this about performance issues mentioned in FAQ about capturing high resolutions?