Database of Virtual Instrument Track Delays
Have you noticed that your orchestral mockups don't sound exactly on time, even if you have the notes perfectly quantized? This is due to a slight delay a lot of music libraries come with when triggering the samples.
To compensate for this, you should use negative track delays with different values based on which sample library you are using. Instead of finding these values manually, the database below is a helpful resource (external link - not created by me).