I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

const visible = this._getVisiblePages();
    const visiblePages = visible.views,
      numVisiblePages = visiblePages.length;
    if (numVisiblePages === 0) {
      return;
    }
    const newCacheSize = Math.max(DEFAULT_CACHE_SIZE, 2 * numVisiblePages + 1);
    this._buffer.resize(newCacheSize, visiblePages);
    this.renderingQueue.renderHighestPriority(visible);
    this._updateHelper(visiblePages); 
    this._updateLocation(visible.first);
    this.eventBus.dispatch("updateviewarea", {
      source: this,
      location: this._location,
    });
  }
  containsElement(element) {
    return this.container.contains(element);
  }
  focus() {
    this.container.focus();
  }
  get _isScrollModeHorizontal() {
    
    
    return this.isInPresentationMode
      ? false
      : this._scrollMode === ScrollMode.HORIZONTAL;
  }
  get _isContainerRtl() {