Yes the 5400 drive would be noticeable slower than 7200 drive. both are still extremely slow compared to a full blown SSD The Samsung 850 Evo are prices fairly completive now days. A 500GB one would probably do you, with an USB 3.0 Up to 3 TB External you could store conveniently your excess data
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro