If you have been suffering from extremely slow data copying from the computer running Windows 7 or Windows 7 SP1 to blu-ray disc then here is good news for you, Microsoft has acknowledge this issue, the issue is affecting users while trying to copy data of 10GB or more to Blu-ray disc where copy operation could literally take a day to complete.
Whereas same operation Windows XP completes faster compared to Windows 7 SP1. As per Microsoft, the issue is because of redundant error checking in the Universal Disc File System driver (Udfs.sys) code. This behavior slows the speed of the write operation after a specific amount of data is written to the disc.
Microsoft has also released a hotfix Fix381302 for Windows 7 & Windows Server2008 R2 SP1 users, which can fix slow data copying issue. Please note that Service Pack 1 doesn’t come with fix and users affected with this problem must download hot fix manually and install it. Though Microsoft has promised to include this fix in Service pack 2, but it could months for Microsoft to release Windows 7 Service Pack 2.