This may sound trivial but if you are running other application (in the background also) such as backup utilities that often comes with external drives or Time Machine, virtual drives, etc..., it could interfere with Logic.
5400rpm... I am not an expert, but this seems marginal performance...
LogicPro 10.6.3, MainStage3.5.3
MBPro 17", Core2Duo, 8G, OSX 10.12.6
MacPro, Xeon 6Cores, 64GB, OSX 10.15.7
ULN8, MOTU MIDI TP-AV, C4, MCU Pro, KorgNano, Novation SLMkII
AAS, NI, Celemony, Spectrasonics, Korg, Arturia, etc...
PC, iPad3(V-Control & LogicRemote), AtariST(Notator SL), Several vintage gear