Hard Drive Partitioning Speed

So in my new computer i have two HDD's one has my OS installed and programs only. The second has my personal and media files. I did this so that all those personal and media files would not slow down my first HDD with my OS on it, this was recommended by many friends of mine and also many people online. My first HDD is 500gb with 4 partitions. Partition one has my OS files on it, the other three are empty. The speed is great but now that i have collected so much data my second HDD is full and i need more space to put my data. So this is my question if i start putting data on those other 3 partitions will i loose that speed.