How to get multiple form-based activities in a single pageload call

if you use the same mbox name, then yes, in your delivery response, all 50 should come 

Hi ​@PrasanthV,

You can do this in one call, as long as you either - target everything to the same mbox, or request multiple mboxes in a single delivery request.
With at.js 2.x, adobe.target.getOffers() supports passing an array of mboxes (execute/prefetch), so you can fetch many form-based activities in one pageload call and then apply them via applyOffers().
For native mobile / server-side, the Target Delivery API also supports requesting content for multiple mboxes in a single call (single/batch), and “prefetch” is a common approach for this.