There are simple techniques of splitting a big VCF file that don't lead to any data loss if applied correctly. The easiest way would be to use special software called Softaken Software vCard Splitter which will let you easily break one big VCF file into several smaller VCFs with no risks to your contacts. All that you have to do is simply import your file, review it and click on the Split button. The software will create new files for your contacts automatically. Your important data such as name, telephone, email, or address will not be changed during this process, it is faster and safer than any manual technique. It works well for such services as Outlook, Gmail, and even your mobile phones' contacts.