Thanks for your replies.
The problem is with Desktop version. I'm not using any kind of network drive, running from local and fast NVMe disk. The problem is not with the amount of data displayed on console, it appears as soon as I open RStudio, or after I clear the console. The "Limit console display to a subset of total content" option doesn't seem to help.
I already tried all the options for the rendering engine, as well as under General/Graphics in 1.4 version, I don't see much of the difference.
Let me also mention that, as my laptop has both NVIDIA and Intel graphics, I tried with both, using NVIDIA proprietary driver and then Intel driver, again to not much difference.
Admittedly, I don't have previous experiences with IDEs/editors based on Chromium, like Atom etc. However, I can confirm that some other such applications, like Slack, are very problematic too on my HiDPI screen, so that pretty much explains it.
Anyway, thanks again for your help. I guess I'll try to live with smaller RStudio window, and hope for improvements in the future (version 1.4 indeed works slightly better).