Not really. Your GPU is massively out pacing anything that CPU can deliver.
It would be more sensible to replace it with a contemporary quad core or better. That would mean a new motherboard and ram as well.
Best you can do with an A4 3300 is maybe replace it with an Athlon K quad core. That would be fairly inexpensive and get you the most out of the hardware you have now.
Depends a lot on your motherboard what CPU is compatible though.