значительно уменьшаться
• Circulation losses may be substantially (or greatly, or vastly, or considerably, or appreciably, or drastically, or seriously) reduced.
Русско-английский научно-технический словарь• Circulation losses may be substantially (or greatly, or vastly, or considerably, or appreciably, or drastically, or seriously) reduced.
Русско-английский научно-технический словарь