You should always use Web Workers. And in our current landscape of frameworks it’s virtually impossible.
Did I get your attention with that? Good. Of course, as with any topic, there is nuance and I will lay that all out. But I have opinions, and they are important. Buckle up.
Note: I hate the “emerging markets” terminology, but to makes this blog post intuitive to as many people as possible, I’ll be using it here.
Phones are getting faster. I don’t think anyone will disagree with that. Stronger GPUs, faster and more CPUs, more RAM. Phones are going through the same rapid development desktop machines did in the early 2000s.
Benchmark scores taken from Geekbench (single-core).
However, that’s just one edge of the distribution. Slow phones are stuck in 2014. The process to create the chips from half a decade ago has gotten so cheap that phones can now be sold for around $20, and cheaper phone will reach a wider audience. ~50% of the world are online, meaning that the other ~50% are not. However, these offliners are coming online and are predominantly located in emerging markets, where people simply can’t afford any of the Wealthy Western Web flagship phones.
At Google I/O 2019, Elizabeth Sweeny and Barb Palser handed out Nokia 2 phones at a partner meeting and encouraged them to use it for a week to really get a feel for what class of device many people in the world use on a daily basis. The Nokia 2 is interesting because it looks and feels like a high-end phone but under the hood it is more like a smartphone from half a decade ago with a browser and an OS from today — and you can feel that mismatch.
To make things even more extreme, feature phones are making a comeback. Remember the phones that didn’t have a touch screen but instead come with number keys and a D-Pad? Yeah, those are coming back and now they run a browser. These phones have even weaker hardware but, maybe somewhat surprisingly, better performance. That’s partly because they have considerably less pixels to control. Or to say it another way: relative to the Nokia 2, they have more CPU power per pixel.
The Nokia 8110, or “Banana phone”
While we are getting faster flagship phones every cycle, the vast majority of people can’t afford these. The more affordable phones are stuck in the past and have highly fluctuating performance metrics. These low-end phones will mostly likely be used by the massive number of people coming online in the next couple of years. The gap between the fastest and the slowest phone is getting wider, and the median is going down.