I might just have found the actual bottleneck regarding VR-performance...
As the Rift S comes w/ DisplayPort (MiniDP-Adapter) only, I'm using a USB-C to DP-adapter.
Checked NVIDIA Control Panel a minute ago:
I assume the USB-C-port is "hard-wired" to the Intel-Graphics-Chipset, not the RTX 2060, hence the render-lags?
Would someone know / be able to confirm this?
Is your screenshot above showing just the notebook screen with no external monitors connected and can you check or provide another screenshot when the RIft S is connected through the type-C output?
You can also connect an external monitor through the type-C connection and check the information in the Nvidia display properties as well as Intel display properties to see which graphics chip it's connected to.
If you find any of the display outputs are hardwired to Intel graphics and want to go through the trouble of running a benchmark, compare the scores to get more confirmation that different graphics chips are being utilitized, but the screenshot above seems to indicate that both the HDMI output and display port/type-C output are running off the Nvidia graphics, so want to make sure you checked this thoroughly.
Expecting your HDMI output is hardwired to the Nvidia graphics though (and hopefully your type C display output, but your feedback seems to indicate this is not the case although would like to get more confirmation of this from you), so check this too (you should notice your HDMI monitor doesn't appear under the Intel graphics settings, but appears under the Nvidia display settings).