Ihave 16.0 installed memory, 15.9 ,available. Yet my laptop is very slow. .

Greetings to all, I have a windows 10 64 bit. I recently had a 1Tb internal hard drive installed. I have 16.0 installed memory(RAM), with 15.9 available, Yet accessing internet locations takes a long time. Why is that? What can be done to correct it? How did this happen? Thank you. Ldxrunner