I just bought a ASUS PB287Q monitor and hooked it up (via HDMI) to my ASUS N550JK-DS521H. Everything works...but the performance of rendering on the external monitor is terrible. The experience on the laptop monitor is however perfect as before.
I've tested with and without monitor mirroring in the system settings. It has no effect on the sluggish experience. I'm suspecting that some kind of software buffering is involved in rendering to the second screen as there is slight delay in the external monitor rendering compared to the builtin screen rendering in mirrored mode.
Is there any use in trying another desktop such as GNOME?
Can I somehow tell Ubuntu to instead use the NVIDIA card (instead of the defaulted Intel) when rendering the external monitor?
I'm sitting on 15.04 with its default (compiz) desktop. No software nor physical rotation is involved.
lspci -k | grep -EA2 'VGA|3D' outputs
00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06) Subsystem: ASUSTeK Computer Inc. Device 11cd Kernel driver in use: i915 -- 01:00.0 3D controller: NVIDIA Corporation GM107M [GeForce GTX 850M] (rev a2) Subsystem: ASUSTeK Computer Inc. Device 11cd Kernel driver in use: nouveau
Update: Ok, I've now installed
nvidia-prime and rebooted.
direct rendering: Yes server glx vendor string: NVIDIA Corporation OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce GTX 850M/PCIe/SSE2 OpenGL core profile version string: 4.4.0 NVIDIA 346.59 OpenGL core profile shading language version string: 4.40 NVIDIA via Cg compiler OpenGL core profile context flags: (none) OpenGL core profile profile mask: core profile OpenGL core profile extensions:
But still the same problem with sluggishness (only on external monitor). I'm suspecting compiz... What to try next?
Update I'm on NVIDIA now since
prime-select query returns