They claim a high availability, but no data on P90 or P95 response times. There is no SLA on their free plan.

While I appreciate the free service, I work in the web performance space. I've seen third party widgets from big name companies like Optimizely, Tealium, Pubmatic, and Adobe have slow response times for critical content, delaying the entire waterfall for major sites. Its hard for the big companies to whom you actually pay money to get this consistently right in a way that doesn't slow down the page.

We've had a ton of people taking cracks at this. From Google and Microsoft with their "Ajax" CDNs a decade ago, to unpkg and Cloudflare. And yet I still have not seen any of these special JavaScript-specific CDNs ever beat a vanilla CDN dumbly serving JS packages that you yourself have bundled and optimized under normal site traffic.