I need some PC tips (RAM/memory)

[theARTIST0017]

So my PC has been sluggish most likely because of the RAM but I don't have enough money to buy more RAM sooo

I used disk defragmenter

I used disk clean-up which freed 17 gigs of space from my hard-drive

I emptied my recycle bin to clear another 9 gigs of space

I uninstalled unnecesary programs i don't use or need to clear about another 2.5 gigs of space

I also deleted my browser cookies (Mozilla Firefox)

My browser is still being slow. Even if I use the task manager to close unwanted tasks it still doesn't help much. Any tips?