Acrobat take so long to delete form fields when multiple fields are selected. It depends on how many form fields are selected across opened Documents. In other words, if you have an opened document with 2 or 3 form fields selected while you are deleting form fields on a different one (another one), it will take 5 to 10 seconds to delete desired form fields (as invoked and desired by user to delete form fields on a document). On a different scenario if an open Document has 40 Form Fields selected while deleting Form Fields on a different opened document (another one), it will take around a minute or more to delete desired fields on current/active document.

The more form fields are selected across open documents, the more it will take to delete form fields on a document.

As more form fields are selected across opened documents, more time it will take to deleted form fields on a "working document" (working document = document you are processing to deleted Form Fields). It has been necessary for me to make sure of not having many form fields selected across opened documents when going to delete form fields on a document to avoid spend a lot of time on the delete form fields process.

It is something with Acrobat and it is not something with Acrobat installation because it has happened (exactly happened) to me on different Computers and now on a Workstation Laptop one. It happens with the New Acrobat Interface and on the previous Acrobat Interface which is the one I'm currently using.