Please note the performance impact of retrieving all records into memory. Depending on the data retrieved, this could result in severe performance degradation and thus is advisable to have a limit on the data retrieved.

You could consider using a report definition instead of Obj-Browse to get data in pages if the data fetched is huge.

If you want to achieve this using Obj-Browse, then it supports by default 10,000 records only, and browsing these many data using Obj-Browse will be a hug permormance impact. Instead you can do it with Report Definition or List- view to get it, And if it possible Configure the Report definition on D_Page.

It was not idle to pull entire records and mantain  them in Clipboard. The resources will be contsrained if you try to retrive large amount of data.for your question if you give max records as zero or left blank system will pull all the records (till 10,000). If you want to pull mor than 10000 either you need to sepcify the count in the maxrecords or you need to go with report definition. system thows an Alert PEGA0042 if database query took more than threshold of 1,000 ms . 

Efficient way is to go with the parameterized data pages to pull only the required  number of records

Setting the value to 0 pulled all the records, As from the performance point of view this acitivity is going to be run only once that too when no users are logged in.