Flow Byte

Resizeer is a WordPress plugin designed to help you manage your media library more efficiently, ensuring your images are optimally sized for both web performance and quality. With Resizeer, you can automate the image resizing process, whether you’re uploading new images or dealing with existing ones in your library.

Resizeer

Optimize your images automatically and forget about resizing and compressing them manually before uploading to your WordPress site.

riotweb

About
This plugin will instantly speed up your WordPress website when the plugin is activated. 
Gzip is the most popular and effective compression method currently available and generally reduces the response size by about 70%!
Important 
This function changes your .htaccess file. In some cases this might result in a 500 error. If you’re not sure whether you can run Gzip ask your hosting company. 
The only way to fix this is to be able to edit the .htaccess file from outside WordPress (via FTP).
Gzip Checker 
NEW – You can now check if Gzip is enabled for your website. Go to “settings” and select the “Instant Gzip Compression” tab.

Instant Gzip Compression

Speed up your Wordpress website with this Gzip compression plugin.

Resizeer vs Instant Gzip Compression