I am seeing a weird and somewhat intermittent issue when rendering xaringan slides. Most of the time when knitting (either keyboard shortcut or Knit button) the file will render and then preview as expected in a couple of seconds.
Every third or fouth knit (roughly) the rendering will occur (expected output shows in the R Markdown tab) but the Viewer pane will blank and then entire RStudio interface will lock up - typing in the console does not work, tabs cannot be changed, buttons cannot be clicked, etc. These interactions are being buffered, as when the gui becomes responsive again the keystrokes will appear, and buttons will be clicked. This lock up can last from 5 seconds to upwards of 30 seconds.
In looking at Activity Monitor these lock ups seem to correlate with a QtWebEngineProcess being pinned at 100% cpu for the duration.
I have not come across a good way of replicating this beyond repeated attempts at knitting the xaringan document. I have not seen this behavior with basic RMarkdown html documents. This behavior occurs with both the current preview and stable releases and all necessary packages updated.
This behavior can be seen with the builtin xaringan examples, e.g. ki-demo.Rmd and fc-demo.Rmd however the length of the hangs tends to be shorter which may have something to do with their length.
The yaml of my xaringan slides is as follows:
---
title: "---"
subtitle: "---"
author: "---"
date: "---"
output:
xaringan::moon_reader:
css: ["slides.css"]
lib_dir: libs
nature:
highlightStyle: solarized-light
highlightLines: true
countIncrementalSlides: false
ratio: "16:9"
---
removing the custom css and lib_dir does not prevent the hanging behavior.