Hi,
Yes, it takes time because we need to submit each an every question for evaluation. it is also dependent on sever that how fast it can serve.
However, if there are 10 questions then only the single ajax call is sent for single question but if there are more questions then for each question single ajax call is not sent.
If there are 100 questions then first it's divided into 10 parts and in 1 ajax call 10 questions are saved and so on.
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For now please try to deactivate all third party plugins and then retake the quiz. let me know if it resolves.