My 2009 iMac, though not a laptop, benefitted from a swap to an SSD from the HD. At the same time I added more ram to total 8 GB. It works very well for me.
That's also my experience with a 2009 MBP. Swapped out the HD for an SSD, maxed the RAM, and put in a new battery, and had an adequate machine for most daily tasks.
It showed it's age and lagged a lot with more intensive software like Fusion 360, but overall was a pretty good machine for 10 years.
