From the URL you provided, the API responses don't look very big.
Generally, it's rarely necessary/beneficial to store API responses in variables. Instead, it's usually better to access the data directly from the API response. That way, the UI will also update if the API call is re-fetched later.
When I open the editor on your start branch I don't experience any lag. Not sure if any logic on the page would work differently for you than others? (perhaps if you're using some sort of authentication)
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