As my answer came close to a blogpost, I figured writing it down into a real blogpost as well. The shortest answer to this sitespeed question in regard to 5G is: no, it won't make your sitespeed issues go away.
The brief answer is: there is more to mastering and achieving optimal performance, than the internet speed alone. As a result, 5G won't fix your performance issues.
Basically, there is no need to have slow loading webpages in the current era, based on free optimizations already given by browsers, network infrastructure, and hosting providers.
Rather have full-length answer? Keep reading:
Why 5G won't fix your webshop's sitespeed issues
Let's elaborate on why you shouldn't get your hopes up over 5G, fixing your pagespeed or sitespeed issues all together. When your webshop is suffering from bad pagespeed and performance, you might notice a remarkable differences. But at the same time, consider the following:
Sites won't load (much) faster on 5G
In the Netherlands, reaching the speed of 10 gigabytes per second, or 1 gigabyte per second for consumers, 5G might be 20 times faster than 4G, on paper. This could mean that downloading a 650MB Netflix movie theoretically takes:
- 2 minutes on 4G;
- 5 seconds on 5G.
At the time of writing, an Amazon product page is 43.4MB on a desktop and 14.5MB on a mobile device. Quite a lot, but such pages should be downloaded in the wink of an eye on 5G, one would assume or even hope. When looking at Amazon's performance score and individual metrics as analyzed by PageSpeed Insights, they have other concerns than 5G and thus internet speed alone. Amazon won't profit as much as one would expect, considering only download speed.
These concerns are partially explained below as well. At the same time, Amazon may be considered as an exception. For example, a bol.com product page is 2.2MB in size, while the HTML page itself is around 60 kilobytes (compressed). How much faster will 60 kilobytes be downloaded with 5G internet connection.
As the average webpage won't be nearly the size of a season of a Netflix show nor an episode, the speed gains won't be as big as when streaming or downloading a Spotify audio, a Youtube video, tv-series, a Playstation game or a Windows update.
Conclusions: loading time improvements might be less noticeable as the difference between 3G and 4G.
CPU boundaries impacting performance on smartphones
Internet speed is only one piece of the puzzle when it comes to pagespeed. Even when resources are fetched within 1 millisecond, the device of your users still has to do the homework. Think about tasks such as parsing, executing and rendering code.
As not all of your users will be on the same device, the time needed for these tasks may vary as well, based on other factors. If all of your users use iPhone 11 instead of legacy devices, you might be ok. Or maybe not, if other users have already opted to go elsewhere due to suboptimal performance.
Conclusion: Faster internet won't fix hardware limitations.
HTTP/2 and render blocking resources
We can only determine if 5G will speed up our shop, if we know how browsers work. We already have HTTP/2, meaning simultaneous downloads are already possible. Only if you have a very big bundled file or you don't have render blocking resources, 5G will make a noticeable difference.
But even today, it is likely there are render blocking resources in play, even within your shop.
Conclusion: Your shop will be as bad as your weakest link, namely render blocking resources.
Time to First Byte
5G is improving latency and thus the time it takes to get a response, once a webpage requests has been send. Besides the time it takes to receive a request and send a response, the response still has to be generated. This part is unrelated to 5G. The most heard solution is finding yourself another hosting provider. It isn't that simple though. For example within the website and webshop niche, Wordpress or Magento are known for having suboptimal server side performance. This won't be fixed with 5G.
Conclusion: 5G won't address network latency as a whole, TTFB still being a potential bottleneck.
Reduced network latency
What about the rest of the network latency, the sending and receiving part? 5G promises latency around 1 millisecond. That's impressive, although real network latency is likely to be around 10 milliseconds. Moreover, the radio connection from your smartphone to the tower is 5G, the connection from the tower to the rest of the “core” network is still 4G. Even in the USA, being an early adopter of 5G, widespread deployments of 5G standalone networks are still several years away.
Even on today’s cellular and WiFi networks, network latency is measured in tens of milliseconds. The latest version of 4G LTE Advanced Pro has evolved to the point that it does a pretty good job on latency already, making latency difference quite small and maybe even unnoticeable.
Conclusion: Websites aren't the ones benefitting the most from latency improvements of 5G.
5G speeding up image download
However, we already have lazyloading, i.e. either native image lazyloading or using libraries. Most likely, there is lazyloading in place already, even within your shop, so there is no UX gain left when having 5G.
Conclusion: Due to lazyloading, 5G won't make a remarkable difference when it comes to images.
Optimal 5G coverage isn't there yet
While the USA and some Asian countries started testing with 5G to accommodate larger cities with 5G connection, the Dutch government is still auctioning the 5G frequencies. Switzerland is further, having 2,000 cell towers, but put 5G on hold due to a suspicion of health issues. But obviously, 5G will come into use some day between 2020 and 2022.
Conclusion: 5G might still take a while
The range of 5G is only 300 meters
5G has a short wavelength, being able to carry a lot of data much faster than 4G. 5G can therefore support approximately 1,000 more devices per meter than 4G. At the same time, it also means the range of 5G is shorter, by about 1,000 feet or 300 meters. That's not even 2% of the range of 4G, which is about 10 miles or 16 kilometers. And as even trees can block 5G signals, there has to be an optimal distribution of those 5G cell towers and antennas. As a result, more 5G cell towers and antennas are needed. Public protests in countries such as Switzerland and the Netherlands are already expected to delay 5G coverage. Installing new cell towers can take up to two years due to legal (or sometimes less legal) actions by the residents.
Conclusion: 5G coverage won't be as optimal as 4G
5G won't give you the speed it promises
At least, maybe not at all times. Remember the moments where your phone signaled 4G, but you nevertheless experienced slow loading pages? Think of 5G as offering a speed range but the actual speeds you get will depend to what network you’re connecting to, how busy it is, what device you’re using, and a few other factors. This table gives you a rough idea of the maximum speeds of each generation of the cell network technology and the average speeds in the real world.
Toon Norp, 5G expert of TNO, the Dutch organization for applied natural sciences, expects that the speed of 5G will be similar to 4G, at least in the early days.
Conclusion: For consumers the real download speed will be below 1 gigabyte per second, instead of its maximum of 10 gigabytes per second, where other factors will play a role as well.
5G compatible smartphones are needed
Even when 5G is around and most of your potential customers are doing their shopping at home, the office or urban areas, don't count on them to buy the newest phone and experience 5G per se. Although most smartphone manufacturers have released 5G devices, most of them aren't compatible with the Dutch 5G infrastructure. At the time of writing, a Chinese manufacturer OPPO is the first to release a 5G device in the Netherlands: OPPO Find X2 Pro.
Conclusion: Although telecom companies might be ready some day, don't expect your users to be compatible.
5G and sitespeed conclusion
5G will be beneficial for a lot of situations and purposes. Think about VR, IoT, gaming, controlling drones, tactile internet, robots, Vehicle-to-vehicle (V2V) communication or even telemedicine, letting surgeons operate on patients in a different time zone. However, compared to all these things, webpages are and will be considerably smaller and so will the noticeable impact will be as well.
Obviously, I can't guarantee that your website's of webshop's loading time won't improve on 5G. But betting on 5G to solve your pagespeed issues might not be the best idea. On the contrary, all (existing and new) users will benefit from fixing fundamental pagespeed bottlenecks. There will be more users on legacy devices tomorrow, than there are today. 5G is only widening this UX gap. On top of that, chances are faster internet will make the web experience worse.