Problem:
Initialize a view with posts that match todays date

Solution:
You can use view's filter "wpv_filter_query" to filter the posts by current date or today's date by default.

You can find the proposed solution in this case with the following reply:
https://toolset.com/forums/topic/initialize-a-view-with-posts-that-match-todays-date/#post-2296447

Relevant Documentation:
- https://toolset.com/documentation/programmer-reference/views-filters/#wpv_filter_query

Problem:
Design principle - creating tens of thousands of relationship instances, performance

Solution:
If we rule out Toolset totally here, even with only WordPress, with such mass content having more than tens of thousands of posts WordPress will also have performance issues. I'm not saying it will not work but it may have impact on performance based on the number of taxonomies, relationship and what filters you add to your view.

In general, performance obviously affects the site speed when you have that many custom post type setup having thousands of posts with the number of taxonomies as well as custom fields. One aspect is how much content you have BUT it depends also on your server configuration (memory,cashing) as well as number of other factors such as how complex your data structure is.

You can find the proposed solution in this case with the following reply:
https://toolset.com/forums/topic/design-principle-creating-tens-of-thousands-of-relationship-instances/#post-2296151

Relevant Documentation:
- https://toolset.com/documentation/legacy-features/views-plugin/how-to-use-views-parametric-search-on-large-sites/