External project drive pros/ cons for midi projects

I’ve been using an external hard drive to house all my Cubase projects ever since I heard that it’s better for system resources to not be reading from and writing to your system drive while recording. However, after some further reading, and watching Cubase videos, I’m wondering if this would add more latency and general problems for largely MIDI based projects, like orchestral mockups. I can see why it would be good for recording audio to, but would a midi performance project suffer worse than just being on my system drive?