I'm noticing this issue also. I just upgraded to the newest RStudio (1.2.1335). When I open RStudio the rsession CPU usage goes right away to nearly 99% without doing anything. Then I try to load a package (in this case dplyr) and I get the error in the image below that keeps repeating and repeating and will not stop. I need to force quit. During this time QtWebEngineProcess get to greater than 100% of CPU, two rsessions are open each with 99% CPU.
When I quit RStudio one rsession seems to stay open using 99% cpu.
Oddly, this seems to be related to R markdown (?). If I load dplyr in the console no problem. If I open a new R markdown and keep the default R markdown code and then try to run a single line of the R markdown this issue comes up right away BUT if I knit this works fine.
Seems to be something to do, for me, with trying to run a single line of code from an R markdown document.
I'm using a MacBook Pro with Mojave, R 3.6