Methods for Speed Optimization in Magento 2
Enable GZIP Compression
Check first that your mod_deflate is on in Apache. You can verify by making an info.php file and then call phpinfo(); You will get the output as server PHP / Apache specification in the browser.
JS Minification and Merge/Minify CSS
Goto Stores>Configuration>Advanced>Developer>JavaScript Settings
Modify the configuration as per the following Screenshot.
For more details: https://magecomp.com/blog/magento-2-enable-gzip-compression-minify-js-css-files-for-speed-optimization/