Replaced Back Hard Drive , rebuild raid , now speeds are slow from the webaccess

Hello, 

 I had a bad drive last week, WD replaced it, I thew it back in the array (RAID 5) 12TB version. Now is seems that the server is not as fast as it normally is. I was wondering do i have to do anything else to get it back where it originally was?

thanks 

Look in the WD tab of the console at the drives.  It is still probably rebuilding