Cursor movement is not smooth under high CPU/GPU load
When the system is under a moderate amount of load, perhaps because GNOME Shell is switching workspaces, switching to the overview, or if Firefox is playing a video the mouse movement is jerky/stuttery and resists movement. Scrolling is also affected in the same way; almost as if events are being dropped.
I can only reproduce this when using GNOME Shell with a dual-monitor setup: 2560x1440 + 1366x768. This does not happen when I am only using it on my 1366x768 laptop screen.
I have a dual-GPU (optimus) render offload setup:
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller]) Subsystem: Dell Device 05f5 Flags: bus master, fast devsel, latency 0, IRQ 43 Memory at f7400000 (64-bit, non-prefetchable) [size=4M] Memory at d0000000 (64-bit, prefetchable) [size=256M] I/O ports at f000 [size=64] [virtual] Expansion ROM at 000c0000 [disabled] [size=128K] Capabilities:  MSI: Enable+ Count=1/1 Maskable- 64bit- Capabilities: [d0] Power Management version 2 Capabilities: [a4] PCI Advanced Features Kernel driver in use: i915 Kernel modules: i915 08:00.0 3D controller: NVIDIA Corporation GK208M [GeForce GT 740M] (rev a1) Subsystem: Dell Device 05f5 Flags: bus master, fast devsel, latency 0, IRQ 47 Memory at f6000000 (32-bit, non-prefetchable) [size=16M] Memory at e0000000 (64-bit, prefetchable) [size=256M] Memory at f0000000 (64-bit, prefetchable) [size=32M] I/O ports at d000 [size=128] Expansion ROM at f7000000 [disabled] [size=512K] Capabilities:  Power Management version 3 Capabilities:  MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities:  Express Endpoint, MSI 00 Capabilities:  Virtual Channel Capabilities:  Power Budgeting <?> Capabilities:  Vendor Specific Information: ID=0001 Rev=1 Len=024 <?> Capabilities:  #19 Kernel driver in use: nouveau Kernel modules: nouveau
I do not have any special kernel options enabled. This is with the latest Fedora 27, which is running GNOME 3.26.2, Kernel 4.15.3-300, Mesa 17.3.4-1.