When embedding a subscription form, the Mailjet code says to embed a script called pas-nc-embedded-v1.js. This actually takes nearly 2-3 seconds to load on the page -- just look at the Network tab in the JS console while the page loads (see attached screenshot). This script is problematic. I recommend the following updates:

• minify/compress the JS file
• tell users to put the script at the bottom of the page, not near the top (where the subscription form is likely embedded)
• host the JS file on a CDN or tell users to serve the file themselves