Macbook Pro Hard drive speed
The first thing you want to do is reference the drive specs to see what it is rated in terms of data transfer speed.

According to C/Net, it has an external data transfer rate of 300MBs (it's a SATA drive, so this is expected)



So, if you are getting a drive speed rating of 50MB/s, things are definitely slow.  5400 RPM is also quite slow to begin with.

Your best option is to upgrade your drive to an SSD.  I have written a post that addresses this very topic.  Have a look here: My Mac is getting really slow, what should I do?