Checkboxes are slow to respond on first load

[KatieWoe]

Test device
Dell
Operating System
Win 10
Browser
Chrome
Problem description
For phetsims/qa#508. Seen in published as well.
When the sim first loads up, the checkboxes on the side are a bit unresponsive and there is a noticeable lag between clicking on them and the effect taking. After the first time, the lag goes away, but it comes back on a new load of the sim. Seemed worse in phet-io when loading a sim with changes made, but that may have been chance.

Visuals

Troubleshooting information:

!!!!! DO NOT EDIT !!!!!
Name: ‪Charges and Fields‬
URL: https://phet.colorado.edu/sims/html/charges-and-fields/latest/charges-and-fields_en.html
Version: 1.0.47 2020-06-12 22:47:43 UTC
Features missing: touch
Flags: pixelRatioScaling
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.106 Safari/537.36
Language: en-US
Window: 1536x722
Pixel Ratio: 2.5/1
WebGL: WebGL 1.0 (OpenGL ES 2.0 Chromium)
GLSL: WebGL GLSL ES 1.0 (OpenGL ES GLSL ES 1.0 Chromium)
Vendor: WebKit (WebKit WebGL)
Vertex: attribs: 16 varying: 30 uniform: 4096
Texture: size: 16384 imageUnits: 16 (vertex: 16, combined: 32)
Max viewport: 32767x32767
OES_texture_float: true
Dependencies JSON: {"assert":{"sha":"7d27130a","branch":"HEAD"},"axon":{"sha":"1fd91832","branch":"HEAD"},"babel":{"sha":"64a5ae27","branch":"master"},"brand":{"sha":"e4981a6a","branch":"HEAD"},"charges-and-fields":{"sha":"797dc613","branch":"HEAD"},"chipper":{"sha":"b5faea63","branch":"HEAD"},"dot":{"sha":"3f60cfcc","branch":"HEAD"},"joist":{"sha":"57af1e31","branch":"HEAD"},"kite":{"sha":"3b656b9a","branch":"HEAD"},"phet-core":{"sha":"bebc92b7","branch":"HEAD"},"phetcommon":{"sha":"a4865924","branch":"HEAD"},"phetmarks":{"sha":"3fdfece0","branch":"HEAD"},"scenery":{"sha":"1802fce2","branch":"HEAD"},"scenery-phet":{"sha":"4608a681","branch":"HEAD"},"sherpa":{"sha":"5ddfccd4","branch":"HEAD"},"sun":{"sha":"4b852127","branch":"HEAD"},"tandem":{"sha":"43ebdfb3","branch":"HEAD"}}

[zepumph]

1. Were the dev tools opens for this?
2. What was the "HTML Output" mode from studio? I would only care about this if it was in "Production"

[zepumph]

Seen in published as well.

Oops, sorry! Never mind about my above questions then.