FPS falls dramaticly when width of stroke of lineString is more then 1

[Lamzar]

OL 6.5. I have a lot of lineStrings on the map (> 8000) and I use simple style function which sets only stroke color with some width:

var styles = {
  'LineString': [
   new ol.style.Style({
		stroke: new ol.style.Stroke({
		  color: 'green',
		  width: 4,
		})
	})
   ]
};

var styleFunction = function (feature) {
  return styles[feature.getGeometry().getType()];
};

The questions:

1. If I set width to 1, I have sutisfying FPS. But if I change the width to any other value, even 1.0001, FPS falls dramaticly. I prepared the sample: https://jsfiddle.net/Lamzar/36zu2oay/15/ and also attached the index.html file with this sample.
2. Does anyone know why Firefox renders lines on the map about a twice or more quickly then Chrome? The described above problem with width also takes place in Firefox, but nevertheless it handles with it with greater performance.

index.zip

[ibrierley]

I'm wondering if this is related to Skia...I think Chrome uses that behind the scenes, apologies if wrong. I noted a similar issue with Flutter I was looking at flutter/flutter#78543 (comment)

[stale]

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