Who did invest time&money to increase store speed on mobile? Was it worth it? Did you see incredible conversion rate growth after that?
I read lots of articles that 1 second of loading costs a 7% drop in overall conversion rate, nevertheless, the most of stores that I have tested with Google Lighthouse show a red-zone speed index. So does my store. And I think is it something I need to fix?
The majority of Shopify stores we work on do not score very well when it comes to Shopify's Speed Score or Google's Page Speed Insights (PSI) tool. It's worth noting that Shopify's Speed Score is based on the same engine that powers PSI (Lighthouse).
A bunch of other metrics go into these scores beyond actual speed/loading times, so I wouldn't get discouraged with a lower score. Like you mentioned yourself, you noticed that most stores you've tested do not score well. You can still have a very fast website with a low score.
We typically see scores range between 10-30, on average.
We have a few articles that talk about the relationship between these analysis tools and your Shopify website if you're interested:
That's not to say these aren't useful tools. However, we don't recommend removing/altering essential functionality of your store just so you can potentially obtain a higher score.
I'd recommend running your site through the Shopify Analyzer (free tool we built for the Shopify community) to see if you have any optimization opportunities. Feel free to reach out to our team at speedboostr.com/contact if you have any questions.