Swift Performance Lite is the most powerful free cache plugin on the market.

Key features:

  • Critical CSS on the fly – Swift Performance Lite will generate critical CSS on the fly for every pages
  • Javascript Optimization – get rid CLS, FID, TBT and LCP issues with powerful script optimization
  • Font Optimization: Force font-display: swap for all fonts, use local fonts
  • Powerful lazyload (image, iframe and javascript) features
  • Built-in Image Optimizer

If you are a theme author you can easily bundle Swift Performance Lite with TGM Plugin Activation

You can define SWTE_AFFILIATE_ID somewhere in your theme (eg: functions.php). If SWTE_AFFILIATE_ID is defined, all upgrade links on the dashboard, settings, e-mails, etc will contain your affiliate ID, so if a customer upgrades to Swift Performance Pro it can be easily tracked.

Example:

define("SWTE_AFFILIATE_ID", "123");

If you are an affiliate you can also create coupons, so you can even provide some special discount for your customers.