What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
To my understanding you are saying that your form is loading very slowly after embedding it into your Google Website.
Please refer to https://www.jotform.com/help/19-Adding-Form-to-Google-Sites to make sure that you've used the proper instruction to embed your form onto your google site.
If this problem continues though then please let us know. Also, please additionally include a link to the page your form is embedded on within your Google Site so that we can investigate if needed.