For those stumbling on this question wondering how to improve their lighthouse score in general, I posted an answer on this topic on another question with lots of general tips.
I'm running PageSpeed insights and my biggest problem is the largest contentful paint, at about 8-10 seconds. Below they list my largest contentful paint element
Largest Contentful Paint element 1 element found
This is the largest contentful element painted within the viewport. Learn More
Element
This is the a paragraph that appears above here
<section class="mainBgImage gbi--716926567-eDXcajFRMpQ2F1s7wNgLk1" style="background-position:center top;background-repeat:no-repeat;background-size:cover;position:relative;opacity:0.99" role="img">
This element is an image that spans my whole website in the background. It was originally a 1.2 MB png that i load using ...GatsbyImageSharpFluid_withWebp_noBase64
with a maxWidth of 1950.
This is the code for how I render it
import BackgroundImage from 'gatsby-background-image';
...
<BackgroundImage
Tag="section"
role="img"
className='mainBgImage'
fadeIn={false}
// style={{objectFit: 'contain', width: '100%' }}
style={{
opacity: 0.03,
backgroundPosition: "center top",
}}
fluid={wheatImgProps}
>
{children}
</BackgroundImage>
And this is the static graphql query
const data = useStaticQuery(graphql
`query LayoutQuery {
wheatImg: file(
extension: {regex: "/(jpg)|(jpeg)|(png)/"},
name: {eq: "wheat-background"}
) {
childImageSharp {
fluid(maxWidth: 1950) {
...GatsbyImageSharpFluid_withWebp_noBase64
}
}
}
}
`
)
Turns out the solution was to split my background image into 2. One for "above the fold"(Whats visible without scrolling) and one for "below the fold". I also found this image compressor website to be one of the most helpful and straight forward when it came to reducing my file size.
I then created an absolutely positioned div which looked like
const BGImg = ({img, className}:{img:FluidObject, className?:string}) => (
<Img
Tag="section"
className={className}
durationFadeIn={250}
style={{
opacity: 0.03,
minWidth:"100%",
objectFit: 'cover',
objectPosition: "center top",
}}
fluid={img}
/>
)
...
<div id='layout'>
<div id='bgImageContainer'>
<BGImg img={above_the_fold_bg} />
<BGImg img={below_the_fold_bg} />
</div>
...
with styling that looked like
#bgImageContainer{
position: absolute;
z-index: -999;
min-width:100%;
min-height:100%;
display:flex;
flex-direction: column;
justify-content: flex-end;
align-self: stretch;
}
#layout{
overflow: hidden;
position: relative;
}