I've been working on increasing conversion rate by attempting to speed up my site speed and hence, reducing bounce rate. I've tried removing apps, compressing images, removing dynamic widgets on my landing page, installing AMP product pages and publishing new themes that claim to be "Fast". However, after all, according to Google's PageSpeed Insights, my rating will always been between 10 - 20/100 and a ~3.0 second First Contextual Paint (FCP).
I'm starting to feel skeptical: I have began analysing the site speed of different themes including and espeically, the fastest rated themes on the market; Booster, Turbo, Shoptimized etc. and these rate similarly if not WORSE. In fact, Shoptimized who claims to run 38% faster than its competitors rated 7/100 on SiteSpeed Insights.
Strangely, other site speed analysis websites rate significantly higher then normal than SiteSpeed Insights and I have discovered that in similar discussions, some state their Shopify stores run tremendously faster than when I test them myself.
Is there something wrong with Google SiteSpeed Insights, Shopify's foundation or my internet (pertaining to SiteSpeed Insights being server specific depending on your region)? Though, if this is true, it doesn't explain my astronomial bounce rate (I witness visitors stare at the fold 5 seconds than leave (17% average scroll from 1000+ customers))
Is anyone experiencing this?
Google PSI score is not equal to page speed (here's a case study with the data: https://speedboostr.com/case-study-google-psi).
It's not just Shopify sites, most ecommerce sites I've tested score low (even giant companies with million+ dollar tech budgets).
It's an automated analysis tool meant to give you insights on potential performance issues. Use it as a guide, not as a score card.
If you'd like to learn more about Google PSI specifically for Shopify sites, here are details + additional opinions: https://speedboostr.com/google-psi-for-shopify.
My advice: Optimize as much as you can but don't worry about arbitrary scores.
As for your your high bounce rate, could be a number of factors. You can post your url in the forums and ask people to review your site. My team also does a Conversion Analysis service, to see that or get ideas for yourself, check the conversion analysis section in this guide: https://speedboostr.com/conversion-rate-optimization-guide/#cro-conversion-analysis
IMO time to first paint is the most relevant metric for bounce rate. That being said, if you are getting warnings about unoptimized CSS, render blocking resources, unused CSS or JS then the theme is not as well thought out as it could be. Certain factors that Google judges on may not have a big impact on the first contentful paint, but others could. If you are concerned about SEO it could absolutely have an impact. I'm always a little bit disappointed that Shopify does not further optimize their themes. Most the suggestions Google is making are very practical and make sense to implement.
With all that said, i have been in the same position as you, having to choose a theme among imperfect options. You can take some comfort in the fact that everyone else is being forced to do the same thing. Wordpress Woo commerce/Shopify/Big Commerce all have the same problems so if you're thinking about these things you are probably already ahead of the crowd. If you drive most of your traffic from ads then i'd be very focused on time to first paint. If you are concerned about SEO then the problem is more serious and you have to think about it more carefully.
Are you familiar with the Chrome browser dev tools? You can simulate what a visit to your site looks like on different internet connections, and without any caching that may be affecting how the site loads on your computer.