Many users reported "terrible" preview lag immediately after updating. Render Errors:
While Build 177 was the launch version, users are generally encouraged to update to the final stable version (Build 416) for improved stability. Official files can be accessed through the following channels: Boris FX Forum Official MAGIX Download Center sony vegas pro 1500 build 177 patch link
Compare the output to the checksum listed on the source page. Many users reported "terrible" preview lag immediately after