Hi @OussamaMerhi,
I checked your survey and the load times in 3.12, 3.13 and 3.14 beta. They are all similar and expected due to the large number of questions, and more importantly the large numebr of expressions, relevant and calculations, this is what causes the slow loading time.
If you are seeing a difference recently, compared to earlier, I believe it is related to adding more hidden fields and additional expressions, that are taking longer to load now.
Regards,
Phil.