My suggestions would be to display subform results by a set number of result eg 1-10, or 1-20, etc. This will allow users to see a small subset of the subform results and increase page load times. 

I have many instances where I have 100+ subform rows and raised an issue about slow performance at https://help.zoho.com/portal/en/community/topic/form-load-is-very-slow#2266000004566169

Zoho, can you please implement the feature to improve page load times?

Thanks