If. There are two failure points here, both of which are so frequent that I can't even recall seeing an exception.
One, if your first page load tries to load a full page, instead of just some JS that bootstraps the process of loading of the rest of the page, which lets the first load finish before execution. Better yet, it should load the absolute minimum bit of JS site kernel. Then, the first load is likely to succeed on a slow/spotty connection, and we can skip to problem #2 below. This isn't being done correctly in most of the sites I visit for some reason; the first page is either attempted to be downloaded in full, or the "skeleton" of the UI is the piece that always loads the longest.
Two, loading UX. You have a loaded UI skeleton with boxes that need to be filled via further requests. Or, I've clicked on something and a subsection of the site needs to be refreshed. What happens is either nothing, except the SPA getting unresponsive, or I get the dreaded spinners everywhere. If the requests succeed, the spinners eventually disappear. If they don't, they don't. Contrast it to the pre-JavaScript style: if something needs reloading, my page is being rendered essentially top-to-bottom, complete bit of contents popping up as they're loaded; the site is usable in partial state, and if anything breaks, I get a clear error message.
Can this two problems be solved correctly in client-side rendered code? Yes. Can SPA be faster than full page loading? Yes. Is it usually? No, because web development is a culture. When a company decides "let's do SPA" or "let's do client-side rendering", they unfortunately inherit almost all the related dysfunction by default.
One, if your first page load tries to load a full page, instead of just some JS that bootstraps the process of loading of the rest of the page, which lets the first load finish before execution. Better yet, it should load the absolute minimum bit of JS site kernel. Then, the first load is likely to succeed on a slow/spotty connection, and we can skip to problem #2 below. This isn't being done correctly in most of the sites I visit for some reason; the first page is either attempted to be downloaded in full, or the "skeleton" of the UI is the piece that always loads the longest.
Two, loading UX. You have a loaded UI skeleton with boxes that need to be filled via further requests. Or, I've clicked on something and a subsection of the site needs to be refreshed. What happens is either nothing, except the SPA getting unresponsive, or I get the dreaded spinners everywhere. If the requests succeed, the spinners eventually disappear. If they don't, they don't. Contrast it to the pre-JavaScript style: if something needs reloading, my page is being rendered essentially top-to-bottom, complete bit of contents popping up as they're loaded; the site is usable in partial state, and if anything breaks, I get a clear error message.
Can this two problems be solved correctly in client-side rendered code? Yes. Can SPA be faster than full page loading? Yes. Is it usually? No, because web development is a culture. When a company decides "let's do SPA" or "let's do client-side rendering", they unfortunately inherit almost all the related dysfunction by default.