The SmartClient uploads and download the records in batches of 50 at a time by default However NetSuite administrators can change the default upload/download batch size of SmartClient by creating a custom record in NetSuite.
SmartClient refers to this record to set the default batch size for your NetSuite account.
Create a SmartClient Setting Custom Record with following details
Include Name Field: true
fields: custrecord_sc_setting_value (free-form text)
Create the following custom records and set the desired batch size
Ex: In order to override the Upload batch size, create a customrecord_celigo_sc_setting with the name of the setting (as above) and set the custrecord_sc_setting_value field value to the new value.
Image below for an example which reduces the Upload Batch Size to 25
Following image shows the custom records created for all data operations
Note: If you have already created the Custom Record for some other setting you need only to add the new fields and then create your new Custom Records.