Before uploading images to your site it is best to save for the web. The better compresion, the faster the load times.
There are a number of sites on the web that will do this for you for free. One tool they we have found and has high reviews is TinyPng – https://tinypng.com/
Tiny PNG has very high reviews., Tiny PNG will support compression of both .jpeg and .png image files.
You can bulk upload images with drag and drop (up to 20 at a time, 5 MB max each). Each image can be downloaded straight to your computer or saved to a Dropbox account.