I recently found out about Photopea which is an online advanced image editor.
You can use Photopea in your browser or install it as an extension in Chrome. This added a shortcut on my desktop allowing me to run Photopea in full screen.
Photopea has the same look and feel as Adobe Photoshop, so is really easy to pick if you already have experience of using Photoshop.
After using it to do some basic image editing, I have to say how impressed I am with it. Performance is that good, you don't actually realise you are using this online.