Swift Performance Lite is the most powerful free cache plugin on the market.
- Critical CSS on the fly – Swift Performance Lite will generate critical CSS on the fly for every pages
- Font Optimization: Force font-display: swap for all fonts, use local fonts
- 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.
If you are an affiliate you can also create coupons, so you can even provide some special discount for your customers.