Google Chart Lags When Embedded Into My Squarespace Site

Hi -

I'm making a website using Squarespace (not live yet) and have run into an issue where a Google Sheets chart stored in my Google Drive, which is actually derived from inputs gathered from my SquareSpace website form and subsequently sent through Zapier, does not instantaneously deliver the Google Sheets Chart back into to my SquareSpace website. 

The flow of the process is: (1) collect data on SquareSpace form, (2) data is sent to Zapier, (3) New Spreadsheet Row is created in Google Sheets, (4) Google Sheet chart is automatically updated, (5) Google chart published and embedded into SquareSpace site as 'Embed' Block - code snipped. 

I have embedded the Google Sheets Chart code into an embed block within my Squarespace site: <iframe width="1140" height="747" seamless frameborder="0" scrolling="no" src="https://docs.google.com/spreadsheets/d/e/2PACX-1vRuIMZe9zC318xX2iGzF5ENynTVfa9aHsXVLNzyyNbtASKsPuh3pCc1KTdoQ7nLDwF_hsA1iheRJhao/pubchart?oid=83063898&amp;format=interactive"></iframe>

The chart on my Squarespace website updates but it takes about 2-4 minutes so the ideal flow isn't useful as I want to show the derived Google Sheets chart instantaneously based on the inputs of the Squarespace form. The Google Sheets data and chart updates in semi real-time (~1 second) but Squarespace doesn't update the Googe chart. Is there anything I am doing wrong or are my expectations simply too high?

Any help is genuinely appreciated.