How many applications can I install on my MBL?

How many applications can I install on my MBL without letting it slow?
CouchPotato + Sickrage can cause slowness or low performance?

Not many I would assume; likely not enough memory RAM so remove some apps if slowed down. The only devices I know of that allow for installing extra memory (a 4GB RAM card) are the WD EX and DL series My Cloud NAS devices…