Is there a maximum size? What are the results? The rule to follow is simple: you must upload images with dimensions appropriate to the maximum necessary size determined by the template. And not beyond. In this way, the time needed to upload it is reduced .
But it also saves resources that are used to upload a photo whatsapp in philippines or an image with superfluous dimensions, useless for the ultimate purpose . That is, to serve content suitable for use, without skimping on the quality of the visual on the website.
There are countless programs to resize and crop a photo, but if you don't want to use Photoshop or Gimp you can take advantage of the simplicity of a tool like Befunky that allows you to modify an image online in a few seconds. But with the professionalism of an image editor that makes Prestashop envious.
LazyLoad
That is, deferred loading , slow. With this solution you can reduce the load of the page at the time it loads. The principle is simple: if a publication has 10 photos, but at the time the above the fold loads 2 of them appear, why make the user wait and engage the browser?
lazyload images
It is better to load photos and videos only when needed. LazyLoad is based on this principle and is increasingly being integrated by default into CMS. In reality, today the use of LazyLoad can be easily implemented on all web pages with a simple attribution of a loading=lazy tag .
<img src="image.png" loading="lazy" alt="…" width="200" height="200">
With a little bit of code effort, you can apply this step to every image and video. On the other hand, there is no point in loading elements that the user may never see (it is not worth it).