If you're looking to upload an image to a blog post, for example, examine the file for its file size first. If it's anywhere in megabyte (MB) territory, even just 1 MB, it's a good idea to use an image compression tool to reduce the file size before uploading it to your blog. Sites like TinyPNG make it easy to compress images in bulk, while Google's very own Squoosh has been known to shrink image file sizes to microscopic levels.
Hey Ted, thanks for the great questions! The peak times refer to your particular time zone, if you are targeting an audience that resides in the same zone as you. You can also use tools to find out when most of your audience is online. For example, Facebook has this built into their Page Insights. For Twitter, you can use https://followerwonk.com/. Many social posting tools also offer this functionality.