Very poor graphic performance from integrated GPU Intel UHD620

I’ve ran two benchmarking programs (glmark2 and hardinfo) on my old PC with an i5-3317U processor with a HD4000 integrated graphics chip and compared them with the same benchmarks on my new PC with an UHD620 integrated graphics chip.

The results are puzzling:
HD4000: 997 in glmark2 and 10834 in hardinfo
UHD620: 801 in glmark2 and 8043 in hardinfo (in glmark2, the benchmark windows even stays frozen on the first frame while the test runs)

On both systems driver is xf86-video-intel as far as I can tell the same memory size 256MB is allocated on both systems. Both have i915 module enabled.

Here’s lspci output

HD4000

00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) (prog-if 00 [VGA controller])
Subsystem: Samsung Electronics Co Ltd 3rd Gen Core processor Graphics Controller
Flags: bus master, fast devsel, latency 0, IRQ 32
Memory at f0000000 (64-bit, non-prefetchable) [size=4M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
I/O ports at 3000 [size=64]
[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
Capabilities: [90] 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

UHD620

00:02.0 VGA compatible controller: Intel Corporation Device 9bca (rev 04) (prog-if 00 [VGA controller])
	DeviceName: Onboard - Video
	Subsystem: Micro-Star International Co., Ltd. [MSI] Device 129c
	Flags: bus master, fast devsel, latency 0, IRQ 192
	Memory at d3000000 (64-bit, non-prefetchable) [size=16M]
	Memory at 30000000 (64-bit, prefetchable) [size=256M]
	I/O ports at 4000 [size=64]
	[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: [40] Vendor Specific Information: Len=0c <?>
	Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
	Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
	Capabilities: [d0] Power Management version 2
	Capabilities: [100] Process Address Space ID (PASID)
	Capabilities: [200] Address Translation Service (ATS)
	Capabilities: [300] Page Request Interface (PRI)
	Kernel driver in use: i915
	Kernel modules: i915

I’ve used Optimus Manager to completely disable the NVIDIA card on the new PC.
Any idea how I could improve the performance of the new GPU? Theoretically it should be at least twice as performant as the old one.

On some machines it is possible to uninstall the xf86-video-intel package. Not sure if that boots on your machine, but probably worth a try (and you must have means to re-install the package it if it doesn’t boot).

And in fact I don’t know how Optimus Manager affects the whole thing…

So, I removed the xf86-video-intel package. Now the benchmarks read: 1832 in glmark2 but 6997 in hardinfo, strange…
Also glmark2 crashed twice.